Conjunctive Management Research Articles

Evaluation of stakeholder knowledge and practices of water use management strategy: Observations from a questionnaire survey in Southern India

Freshwater resources remain unequally distributed in time and space around the world. Water resource frameworks should be designed, planned, and overseen in order to fully meet current and future social and economic objectives. The difficulties grow as the system gets bigger and more complex, with varying spatial distribution of water and insufficient resources, making water re-distribution more difficult. The current study fills such gaps by evaluating several factors influencing conjunctive management. In the current study, an effort has been made to compile the best data on water use, agricultural practises, socioeconomic status, and so on through field surveys in order to comprehend the reality on the ground. Additionally, investigations are being conducted into the causes and barriers that are most likely to have slowed the implementation of conjunctive use of available water resources. Two comprehensive socioeconomic surveys were conducted using the quantitative research methodology in a river basin in Southern India, and the results clearly show that stakeholders are unaware of the most effective agricultural water management techniques and the rationale behind modern irrigation systems. Over ninety-five percent of the total respondents were farmers, with only five percent having basic knowledge of watershed development and conjunctive use water management. The identified gaps and the inference made in the study are in the context of conjunctive water management of agricultural water. The current work may provide useful information on the baseline scenarios for upcoming agricultural water management plans, as well as a useful tool for achieving significant milestones in the agricultural sector. Furthermore, the prepared questionnaire and the data gathered for the study may also be helpful to decision-makers.

Conjunctive surface water and groundwater management in a multiple user environment

The conjunctive use of surface water and groundwater is practiced worldwide as a measure to address water supply uncertainty. This paper focuses on a scenario in which an aquifer is open to multiple users and examines the impact of such an open-access environment on the stabilization function of conjunctive management. We construct a non-cooperative stochastic dynamic game model where multiple users utilize groundwater intake from a common aquifer as a complement to fluctuating surface water. We also propose a simpler baseline applicable to dynamic environments to compute the benefits of the stabilization function when users are unable to adjust groundwater intake to surface water uncertainties. We then apply the model to the real-world case of the water supply environment of the Cao’e River in China. Simulation results show that open access leads to diminishing stabilization values as higher pumping costs due to declining stocks lead to a weakening of users’ incentive to utilize groundwater flexibly. Furthermore, the stabilization function itself is destabilized as the number of users increases. This is because greater groundwater intake and a decline in stocks amplify variations in pumping costs caused by different patterns of surface-water fluctuation.

Groundwater Sustainability and Land Subsidence in California’s Central Valley

The Central Valley of California is one of the most prolific agricultural regions in the world. Agriculture is reliant on the conjunctive use of surface-water and groundwater. The lack of available surface-water and land-use changes have led to pumping-induced groundwater-level and storage declines, land subsidence, changes to streamflow and the environment, and the degradation of water quality. As a result, in part, the Sustainable Groundwater Management Act (SGMA) was developed. An examination of the components of SGMA and contextualizing regional model applications within the SGMA framework was undertaken to better understand and quantify many of the components of SGMA. Specifically, the U.S. Geological Survey (USGS) updated the Central Valley Hydrologic Model (CVHM) to assess hydrologic system responses to climatic variation, surface-water availability, land-use changes, and groundwater pumping. MODFLOW-OWHM has been enhanced to simulate the timing of land subsidence and attribute its inelastic and elastic portions. In addition to extending CVHM through 2019, the new version, CVHM2, includes several enhancements as follows: managed aquifer recharge (MAR), pumping with multi-aquifer wells, inflows from ungauged watersheds, and more detailed water-balance subregions, streamflow network, diversions, tile drains, land use, aquifer properties, and groundwater level and land subsidence observations. Combined with historical approximations, CVHM2 estimates approximately 158 km3 of storage loss in the Central Valley from pre-development to 2019. About 15% of the total storage loss is permanent loss of storage from subsidence that has caused damage to infrastructure. Climate extremes will likely complicate the efforts of water managers to store more water in the ground. CVHM2 can provide data in the form of aggregated input datasets, simulate climatic variations and changes, land-use changes or water management scenarios, and resulting changes in groundwater levels, storage, and land subsidence to assist decision-makers in the conjunctive management of water supplies.

Conjunctive management of groundwater and surface water resources using a hybrid simulation–optimization method

ABSTRACT This study aimed to determine the optimal conjunctive utilization of groundwater and surface water resources in the Halil River basin, one of the most significant study regions in Kerman Province (Iran). Multi-verse optimizer (MVO) and the ANFIS (adaptive neuro-fuzzy inference systems) simulation model, known as the MVO–ANFIS simulation–optimization model, were used for this purpose. Moreover, the optimal exploitation policy for the studied basin was presented. The ANFIS model yielded a coefficient of determination greater than 0.99 in Baft, Rabor, and Jiroft. This model had a high capability to simulate groundwater levels in these three regions. Therefore, the ANFIS model was adopted as the simulation model to predict the aquifer water table in these regions. Regarding the conjunctive utilization of groundwater and surface water resources, the exploitation policy resulting from the MVO–ANFIS simulation–optimization model had a desirable performance by supplying 91.70, 87.75, and 97.58% of the total demands of Baft, Rabor, and Jiroft, respectively. Moreover, results of water system performance indicators, including reliability (82.96, 72.65, 95.07), resiliency (70, 53.47, 80), vulnerability (29.54, 25.64, 17.02), and sustainability (74.24%, 66.10%, 85.78%) in the mentioned regions, respectively, showed the appropriate performance of the proposed model for the simulation–optimization problem.

How best to incorporate conjunctive water management into international water law: legal amendment, instrument coupling, or new protocol adoption?

International water conventions—e.g., the 1997 United Nations Convention on the Non-Navigational Uses of International Watercourses—include positive but insufficient focus on groundwater and its interaction with surface water. As such, a growing body of literature has proposed modifications to existing frameworks to enable consideration to surface and groundwater and their interactions. While this literature places considerable focus on coupling and amending existing legal frameworks, elaboration and evaluation of a new protocol on conjunctive water management comprises a key gap. To fill this gap, this paper seeks to answer the following question: does formulation and adoption of a new “conjunctive” protocol provide more value than existing proposals centered around modifications to existing law? This paper seeks to compare benefits associated with current proposals to strengthen the international legal framework for management of surface–groundwater interaction, vis-a-vis adoption of a new protocol on conjunctive management of transboundary freshwaters. To do so, the authors use doctrinal legal methods to analyze the existing main instruments globally assessing the degree to which they consider key interlinkages between surface water and groundwater. Then, the paper examines the concept of conjunctive water management and deduces tenets that should be pursued in shared waters to achieve this objective. To identify the preferred option to support conjunctive water management in international water law, the paper explores the degree to which existing proposals vs a new protocol enable an embrace of these tenets of conjunctive water management. The paper finds that while a new protocol may add greater value in advancing conjunctive water management, multiple options can and should be concurrently pursued. In particular, the authors argue that new protocols to the existing treaties must be adopted in combination with the amendment of the Draft Articles on the Law of Transboundary Aquifers. Benefits of doing so include more effective management of transboundary freshwater resources that are interconnected hydrologically, a less fragmented and more consistent international water regime, and ultimately more benefits accruing to the populations and environmental goods dependent on shared water resources.

Implementing conjunctive management of water resources for irrigation development: A framework applied to the Southern Plain of Western Nepal.

Climate variability and insufficient irrigation are primary constraints to stable and higher agricultural productivity and food security in Nepal. Agriculture is the largest global freshwater user, and integration of surface- and ground-water use is frequently presented as an strategy for increasing efficiency as well as climate change adaptation. However, conjunctive management (CM) planning often ignores demand-side requirements and a broader set of sustainable development considerations, including ecosystem health and economics of different development strategies. While there is generic understanding of conjunctive use, detailed technical knowhow to realize the CM is lacking in Nepal. This article presents a holistic framework through literature reviews, stakeholders consultations and expert interviews for assessing CM and implementation prospects from a systems-level perspective. We demonstrate the framework through a case study in Western Nepal, where climatic variability and a lack of irrigation are key impediments to increased agricultural productivity and sustainable development. Results show that knowledge of water resources availability is good and that of water demand low in the Western Terai. Additional and coordinated investments are required to improve knowledge gaps as well as access to irrigation. There is therefore a need to assess water resources availability, water access, use and productivity, to fill the knowledge gaps in order to pave pathways for CM. This paper also discusses some strategies to translate prospects of conjunctive management into implementation.

Modeling Surface Water–Groundwater Interactions: Evidence from Borkena Catchment, Awash River Basin, Ethiopia

The availability of sufficient water resources is critical for sustainable social and economic development globally. However, recurrent drought has been a precursor to inadequate water supply in the case of Borkena Catchment, Awash River Basin, Ethiopia. To support the conjunctive use and management of surface water and groundwater in Borkena Catchment, an integrated model was developed using the SWAT–MODFLOW model. The model was designed to operate on a monthly time scale. The change in the water balance obtained from the SWAT–MODFLOW model provides a quantitative means to assess the effect of the climate variability and changes, as well as the impact of human activities, on water resources. To advance the understanding at the regional and local scales, surface water–groundwater interactions in the Borkena Catchment geochemical information and piezometer maps were integrated. The results show that the groundwater recharge in the study area is approximately 122 mm/a. The surface water–groundwater interaction results show that the areas around Harbu and Dessie are characterized as losing rivers, while the areas around Kemisse-Chefa and the highlands of Kutaber, where the Borkena River originates, are characterized as gaining rivers. A geochemical analysis indicated that there is an inter-basin groundwater transfer from the Abbay to the Awash basin. The integrated model generated key temporal and spatial information that is useful for the sustainable conjunctive management of surface and groundwater in Borkena Catchment for climate resilience in the face of climate variability and increasing demand.

Effect of Ecological Water Supplement on Groundwater Restoration in the Yongding River Based on Multi-Model Linkage

Evaluating the effect of ecological water supplement on groundwater restoration quantitatively could produce positive contributions to both water cycle theory and surface–groundwater conjunctive management. Therefore, in this paper, a groundwater flow numerical model has been established after calculating the river section seepage rate using a fuzzy mathematical method in the Yongding River channel. The simulated results show that the model could accurately reflect the real groundwater dynamic features. Then, a data-driven random forest(RF) model has been established to quantitatively evaluate the contributions of the factors which influence the groundwater level variation. The Nash-Sutcliffe efficiency coefficient(NSE) of the RF model is 0.93. It shows excellent ability to identify the rising zone of groundwater level. The study shows that the infiltration capacity is strong in the upstream area of the Yongding River, and the seepage rate is over 0.7. The lowest seepage rate is 0.19 at the downstream end, while the seepage rate in the middle area is basically between 0.4 and 0.7. From 2018 to 2019, the ecological water supplement of the Yongding River has played a significant role in raising the groundwater level along the river channel. Additionally, its contribution analyzed by the RF model to the change of groundwater level is 25%. Groundwater exploitation is the most important variable affecting the groundwater level variation. The impact depth of groundwater level fluctuation reaches about 10 m. The impact range where the groundwater level average uplifts 1.86 m is 502.13 km2. The influence direction gradually changes from around the ecological water supplement section to along the Yongding River channel. The groundwater level variation along the tangential direction of the Yongding River is slowing down. The groundwater level would entirely uplift with 170 × 106 m3/year ecological water supplement of the Yongding River and 35.77 × 106 m3/year groundwater mining reduction in the downstream area until 2035.

Evaluating Spatiotemporal Variations of Groundwater–Surface Water Interaction Using an Integrated Hydrological Model in Huashan Basin, China

Quantifying the spatiotemporal variations of basin-scale surface water (SW)–groundwater (GW) interactions is vital for the conjunctive management of water resources in the basin. In this study, an integrated hydrological model (SWAT-MODFLOW) is used to simulate the SW–GW system in the Huashan Basin. The numerical model was calibrated and validated using the streamflow observations of the watershed outlet and the groundwater levels of the long-term monitoring wells from 2016 to 2020 in the study area. The model results show that the SWAT–MODFLOW can achieve a better fit for the streamflow discharge, compared with the results in the single SWAT model, with R2 (coefficient of correlation) and NSE (Nash-Sutcliffe efficiency coefficient) of 0.85 and 0.83, respectively. The water table fitting results indicate that R2 and RMSE can reach 0.95 and 0.88, respectively. The water budgets analysis demonstrates that the average rate (0.5281 m3/s) of GW abstraction to SW is larger than the rate (0.1289 m3/s) of SW recharge to GW. Moreover, the exchange rate of SW and GW gradually reaches a peak value from June to August, and the lowest value is shown in April, for each hydrological year. Based on the IPPC6 CanESM5 dataset supplied by the Canadian Climate Centre, the regional precipitation scenario subject to climate change was predicted by the ASD (Auto Statistical Downscaling Model) a statistical downscaling method, under the climate scenarios of SSP2_4.5 and SSP5_8.5. The SW–GW interaction pattern was modeled under the future scenarios in the study area. The current (2016–2020) average annual rate of the SW–GW interaction is considered as the base value. Subject to the SSP2_4.5 scenario, the average exchange rate of the SW recharge to GW is 0.1583 m3/s, which is an increase of 22.8%. The average exchange rate of the GW discharge to SW is 0.5189 m3/s which is a reduction of 0.017%. Subject to the SSP5_8.5 scenario, the average exchange rate of SW recharge to GW is 0.1469 m3/s, which is an increase of 14.7%. The average exchange rate of the GW discharge to SW is 0.5953 m3/s, which is an increases of 12.7%. The results can assist in water resource management in the basin, by identifying potential locations of nutrient transport from the aquifer to the river, as well as changes in spatial variability under future climatic conditions.

Seepage and Groundwater Numerical Modelling for Managing Waterlogging in the Vicinity of the Trimmu–Sidhnai Link Canal

The present study focused on the development and application of two computer numerical models, namely, a seepage model developed using SEEP/W software and a groundwater model developed using Visual MODFLOW software. The seepage model was applied to a 38 km length of the tail reach of the Trimmu–Sidhnai (T-S) link canal passing through a severely waterlogged area of 32,000 ha, with a water table within 0–1.5 m from the ground surface; this was to quantify the canal seepage under the present condition (without any intervention) and with the interventions of a concrete lining of the complete prism of the T-S link canal and concrete side protection of the T-S link canal, with the canal bed unlined. The groundwater model evaluated the effectiveness of three waterlogging management interventions, which included: (i) the rehabilitation of the 43 existing drainage tube wells, (ii) the rehabilitation of the existing surface drains, and (iii) a combination of the rehabilitation of the 43 existing drainage tube wells and the rehabilitation of the existing surface drains. The seepage modeling revealed that the concrete lining intervention can reduce 50% of the seepage of the T-S link canal, whereas the concrete side protection intervention can reduce only 21% of the canal seepage. The groundwater modeling revealed that the waterlogging management intervention of the rehabilitation of the 43 drainage tube wells and surface drains can lower the groundwater level from 139.2 to 138.3 m (0.9 m drop), resulting in the mitigation of waterlogging in 45% (14,400 ha) of the severely waterlogged area. The present study recommends that complete concrete lining of the T-S link canal has a huge potential to reduce seepage from the canal, and the combination of the rehabilitation of the 43 drainage tube wells and surface drains also offers a great potential for controlling waterlogging. This intervention can also be considered to mitigate waterlogging from the severely waterlogged area. Cost-effectiveness analysis of the concrete lining of the T-S link canal, the rehabilitation of the 43 existing drainage tube wells, and the rehabilitation of the existing surface drains need to be performed for decision-making and selection of the most cost-effective intervention for implementation. A study needs to be conducted for the development and evaluation of economical and socio-technically feasible and acceptable preventive waterlogging management interventions, including the improved management of irrigation systems, improved irrigation management practices at the farm, improved conjunctive management of surface and groundwater, and improved management of drainage systems at the primary, secondary, and tertiary canal command levels.

Assessment of a Coastal Aquifer in the Framework of Conjunctive Use of Surface Water and Groundwater—The Case of the River Nestos Western Delta, NE Greece

This paper presents research regarding the assessment of the hydrogeological system of the River Nestos Western Delta, NE Greece, during the period of 2019. The procedure included the collection and analysis of relevant hydrological and hydrogeological data concerning the aquifer system of the study area. Specifically, groundwater level measurements and sampling were carried out in a monitoring well network in the shallow unconfined and the deep confined aquifers of the study area, respectively; and surface water sampling was conducted from the River Nestos at selected locations in each of the main drainage canals, as well as in lagoons of the study area; followed by analysis and processing of the relevant chemical analyses results. Finally, piezometric, hydrochemical maps and diagrams were constructed to augment the evaluation of results and the assessment of the system. The present study contributes to the development and management of water resources in the River Nestos Delta area by providing insight into the hydrodynamic and hydrochemical status of the system based on comprehensive contemporary data that can support and justify the compilation of realistic measurements. The conjunctive management of the surface and groundwater in the study area can improve the quantitative and qualitative characteristics of the water. The water level in piezometric maps varies from −4 m up to 16 m for both time periods (May 2019 and October 2019). Moreover, the maximum values of EC are 2700 μS/cm and 2390 μS/cm for the confined and unconfined aquifer systems, respectively. The maximum values of Cl− concentrations are 573.89 mg/L for the confined aquifer system and 514.73 mg/L for the unconfined aquifer system for both time periods (May 2019 and October 2019).

Conjunctive Water Management for Agriculture With Groundwater Salinity

AbstractSalt accumulations in aquifers significantly affect and transform the conjunctive use of surface water and groundwater supporting irrigated agriculture. Salt accumulates in aquifers under many semi‐arid irrigated lands where pumping has lowered water levels enough to prevent drainage of saline groundwater from the basin. This paper provides new insights into optimal conjunctive management of groundwater pumping, recharge, surface water, and cropping patterns with groundwater salinity and hydrologic variability in an irrigated semi‐arid region, such as California's western San Joaquin Valley, reducing agricultural crop yields and revenues. A two‐stage stochastic quadratic model explores this problem to prescribe economically optimal crop mix and conjunctive water operation policies over a 10‐year period with probabilistic annual surface water availability, considering groundwater salinity's harm to crop yields. At low groundwater salinity, agricultural conjunctive use usually pumps most groundwater in drier years, supplied by additional recharge in wetter years. In contrast, at higher groundwater salinity, optimal conjunctive use pumps less in drier years while pumping more in wetter years, when more surface water allows more dilution of saltier groundwater. Reduced pumping in drier years substantially reduces a region's ability to support higher‐value perennial crops and reduces or eliminates lower‐value annual crops in dry years. Artificial recharge with fresh surface water in wetter years can have economic value from slowing groundwater salination which allows more groundwater use in drier years.

1. International Rivers and Lakes / Groundwater

On 29 September, the ministers in charge of water resources of the Gambia, Guinea-Bissau, Mauritania, and Senegal met in Geneva at the initiative of the Secretariat of the 1992 United Nations Economic Commission for Europe (UNECE) Convention on the Protection and Use of Transboundary Watercourses and International Lakes and adopted a declaration recording their will to cooperate in regard to the Senegalo–Mauritanian Aquifer Basin (SMAB). In the declaration, the ministers committed to, among others and in particular: (i) strengthen transboundary cooperation with a view to the strategic, integrated, and concerted management of the water resources of the Aquifer Basin (point 3 of the Declaration) and (ii) to this effect, set up a legal and institutional framework for transboundary cooperation in the sustainable management of said water resources, in conjunction with the surface water resources of the region, including the launch of a negotiation process for the delineation of such framework. The latter will take into account the legal and institutional frameworks already in place for the Senegal River and for the Gambia River—respectively, the Senegal River Development Organization (Organisation pour la mise en valeur du fleuve Sénégal (OMVS)) and the Gambia River Development Organization (Organisation pour la mise en valeur du fleuve Gambie (OMVG)) (point 5 of the declaration). The ministers directed the Regional Working Group of representatives of the SMAB, created in April 2020 with a mandate to establish a transboundary cooperation mechanism for the aquifer, to continue in this role, with new and expanded terms of reference appended to the declaration and with a strengthened capacity to deliver (point 6 of the declaration). Member states of OMVS and OMVG that are not SMAB states—that is, Guinea and Mali—are invited to take part in the process as observers, so as to benefit from the exchange of knowledge and experience, and with a view to the conjunctive management of groundwater and surface water in these states (point 11 of the Declaration). In accordance with the terms of reference appended to the declaration, the Regional Working Group’s (RWG) expanded mandate is to foster cooperation through the exchange and sharing of aquifer data, steer the negotiation process aimed at the establishment of a legal and institutional framework for the aquifer, and secure funding. The RWG will eventually be replaced by a permanent cooperation mechanism as negotiated by the aquifer countries. The RWG will consist of two representatives each from the SMAB states, one representaive each from OMVG and OMVS and one representative from the Sahara-Sahel Observatory. The OMVG and OMVS will provide Secretariat support to the group. The group will meet at regular intervals, and its decisions shall be taken by consensus. Finally, the information that is exchanged in the course of the group activities shall be treated with the confidentiality commanded by multilateral exchanges generally (text of the declaration, French original).

Conjunctive Water Management under Multiple Uncertainties: A Case Study of the Amu Darya River Basin, Central Asia

With population growth, climate volatility, and economic expansion, the conjunctive management of surface–groundwater (SGW) faces great challenges. In this study, a hybrid factorial optimization programming (HFOP) method is developed through integrating factorial analysis, interval linear programming, flexible fuzzy programming, and two-stage stochastic programming into a general framework. HFOP can effectively reflect the multiple uncertainties and quantitatively identify the effects of multiple factors. Then, a HFOP-SGW model is formulated for the middle reaches of the Amu Darya River Basin, where 125 scenarios are analyzed. Some of the major findings are: (i) the improvement of surface-water transport efficiency and the proper use of groundwater can effectively alleviate regional water shortage; (ii) agricultural users have a high risk of water scarcity for all states, especially under a low-flow level; (iii) uncertainties of water-flow levels and risk-reverse attitudes of decision makers have significant impacts on the system’s benefits and water-allocation scheme; and (iv) the surface-water-transmission loss rate and risk perceptions of decision makers are the main factors affecting the system’s benefit’s and water-allocation scheme. These findings can help decision makers obtain desired water-allocation strategies to respond to the variations in water availability.

A quantitative analysis framework for water-food-energy nexus in an agricultural watershed using WEAP-MODFLOW

The challenges of securing safe water supply, sustainable food production and energy conservation make quantitatively analysis of the water-food-energy (WFE) nexus in agricultural watersheds a very important issue. At present, understanding of the complex interactions among the WFE nexus in agricultural watersheds considering the conjunctive management of surface water and groundwater are limited. Based on the WEAP-MODFLOW, this paper proposed a quantitative analysis framework to analyze the interactions among WFE nexus in agricultural watersheds, which considers various scenarios such as water-saving irrigation and drought. The results indicated that this framework can sensitively capture the existing trade-offs and synergies to identify possible comprehensive measures to ensure safe access to water, food, and energy in agricultural watersheds especially in drought conditions. It could also provide valuable assistance for managers and policymakers to think beyond sectors to increase the resilience of WFE sectors under changing environment. Our results show that the impacts of drought have reduced the amount of surface water irrigation due to limited surface water supply, resulting in more than doubled groundwater extraction which may pose a crisis for sustainable use of groundwater, and an increase of 47% in energy consumption for pumping. After integrated management measures, food production rose by 6% while the groundwater level was restored by 0.48 m compared to that under drought, and energy consumption was reduced by 3% compared with water-saving irrigation only. The sustainability index results under different scenarios also reflect the higher sustainability of integrated measures management under drought impacts (SI = 0.13).

Quantifying Streamflow Depletion from Groundwater Pumping: A Practical Review of Past and Emerging Approaches for Water Management

AbstractGroundwater pumping can cause reductions in streamflow (“streamflow depletion”) that must be quantified for conjunctive management of groundwater and surface water resources. However, streamflow depletion cannot be measured directly and is challenging to estimate because pumping impacts are masked by streamflow variability due to other factors. Here, we conduct a management‐focused review of analytical, numerical, and statistical models for estimating streamflow depletion and highlight promising emerging approaches. Analytical models are easy to implement, but include many assumptions about the stream and aquifer. Numerical models are widely used for streamflow depletion assessment and can represent many processes affecting streamflow, but have high data, expertise, and computational needs. Statistical approaches are a historically underutilized tool due to difficulty in attributing causality, but emerging causal inference techniques merit future research and development. We propose that streamflow depletion‐related management questions can be divided into three broad categories (attribution, impacts, and mitigation) that influence which methodology is most appropriate. We then develop decision criteria for method selection based on suitability for local conditions and the management goal, actionability with current or obtainable data and resources, transparency with respect to process and uncertainties, and reproducibility.

The Economic Cost of Unanticipated Water Supply Reductions for Agricultural Producers in the Humboldt River Region

This article develops economic models for a cow-calf ranching operation and an alfalfa hay operation in the Humboldt River Region (HRR) that use surface water for irrigation. The models were built and parameterized through consultation with ranchers and farmers in the HRR in order to represent typical agricultural operations in the region. The models were used to calculate the economic value to an operation of an acre-foot of water not received due to an unanticipated supply reduction. This analysis was conducted to support the conjunctive management of surface and groundwater in the HRR by providing estimates of the economic value of the water that surface water users expect but do not receive due to interference from upstream groundwater pumping. For the cow-calf ranch model, reduced water deliveries impact ranch profits by reducing the amount of low-cost feed grown on the ranch. The increase in average feed costs forces the ranch to reduce its herd size, which lowers the number of new calf births and, as a result, lowers future profits from livestock sales. The cow-calf ranching model predicts an economic value of an acre-foot of water for the cow-calf ranch in the range of $215 per acre-foot for unanticipated supply interruptions that occur in normal water years, and upwards of $290 per acre-foot for supply interruptions that occur during drought. Model results do not provide evidence that the economic value of an acre-foot of water increases with the length of the unanticipated supply reduction. For the alfalfa hay farm model, results indicate that unanticipated reduced water deliveries impact farm profits by first preventing the farm from planting a cover crop during fallow years and then, for more significant interruptions, reducing its acreage of alfalfa hay. The alfalfa hay model predicts that the economic value of an acre-foot of water increases with both the volume of water not received and the length of the unanticipated supply reduction. The economic value of water per-acre-foot predicted by the alfalfa hay model ranges from less than $10 per acre-foot for unanticipated supply interruptions that occur in normal water years, in the range of $100-$200 per acre-foot for single-year supply interruptions that occur during a below average water year, and over $300 per-acre-foot for supply interruptions that occur in successive below average water years.

Long Term Effects of Conjunctive Nutrient Management Practices on Soil Quality in Maize (Zea mays) –Mustard (Brassica compestris var. sarson) Rotation under Rainfed Hill Inceptisol Soils

ABSTRACT The decline in the yields of most of the crops grown in the hill Inceptisol soils of Jammu region of India , is largely attributed to the gradual decrease in soil quality, owing to the poor soil-nutrient management practices. The indicators and the overall indices of the soil quality can be improved to a greater extent through the conjunctive use of organic and inorganic sources of nutrients, instead solely depending upon the inorganic sources. Therefore, a long-term study was conducted with the prime objective to assess the long-term effect of different conjunctive nutrient management practices on soil quality indicators and indices in hill Inceptisol soils of Jammu region of India. The results of the study revealed that after 11 years the order of superiority of the treatments in terms of maize grain yield was 100% NPK (60:40:20 kg ha−1) (T2) (2186 kg ha−1) > 50% NPK + 50% N (FYM) (1961 kg ha−1) (T7) > 50% NPK + 50% N (crop residue) (1789 kg ha−1) (T6) > 50% N (FYM) (1510 kg ha−1) (T5) > 50% NPK (1436 kg ha−1) (T3) > 50% N (crop residue) (1426 kg ha−1) (T4) > control (1183 kg ha−1) (T1). In case of mustard crop, the order of superiority was T7 (1157 kg ha−1) > T5 (960 kg ha−1) > T6 (903 kg ha−1) > T2 (874 kg ha−1) > T3 (783 kg ha−1 > T4 (710 kg ha−1) > T1 (541 kg ha−1). The percent contribution of key indicators toward soil quality index was in the order of available sulfur (S) (31.9%) > microbial biomass carbon (MBC) (31.8) > dehydrogenase assay (DHA) (8.36%) > pH (8.05%) > electrical conductivity (EC) (6.01%) > organic carbon (OC) (4.87%) > available zinc (Zn) (4.56%) > available phosphorus (P) (4.45%). The relative order of performance of treatments in terms of soil quality indices was T5 (1.52) ≥ T7 (1.52) > T6 (1.46) > T2 (1.38) > T3 (1.33) > T4 (1.25) > T1 (control) (0.97). Our study has clearly indicated that after 11 years, the conjunctive use of organic sources of N such as FYM and crop residues in combination with inorganic sources (@ 50:50 on the basis of N equivalents) proved very effective in improving the soil quality indicators and indices under maize (Zea mays) - mustard (Brassica campestris var. Sarson) crop rotation in rainfed hill Inceptisol soils.

Sustainable conjunctive water management model for alleviating water shortage

Water shortage poses a great challenge to the health of population and environment and impedes socio-economic development. Therefore, a comprehensive model is necessary to promote the adaptation of the whole socio-economic system to limited water resources. To achieve it, a sustainable conjunctive water management model (SCWM) was developed. In SCWM, direct (physical) and indirect (virtual or embodied) water consumptions of multiple water resources in future scenarios are projected, and the sustainable performances of various water-saving scenarios are quantified from the perspectives of water resources, economy, and ecosystem under water capping policy. A case study of Shaanxi, a typical water shortage province in central-eastern China, is conducted aimed at conquering the irrational use of surface- and ground-water subjected to the constraint of future total water use quota. Key findings contain optimal possibility of adapting water shortage via saving water through increasing industrial water efficiency to 11.12 m3/10,000 CNY and reducing 40% of agricultural final demand (Summation of direct and indirect water savings of the two scenarios are 41.57 × 108 m3 and 20.27 × 108 m3, respectively.) and nonsynergistic effects of simultaneous decreasing final demand of multiple sectors on water consumption intensity (WCI) of total (all kinds of water) water, surface- and ground-water. To devise effective policies for conjunctive management of surface- and ground-water, positive utility, economic structure and water productivity should be heeded, and proposals emphasize trade-offs between surface water saving and groundwater conservation, water metabolic and socio-economic systems sustainability and negative interaction of multiple sectors on economy and WCI should be framed. The innovation of this study is the development of SCWM, which can provide sustainable solution for future multiple-source water saving management measures thoroughly concerning direct and indirect water and sectorial interactions. The model not only brings insights to Shaanxi's water management but also can be used for other similar arid area.

Simulation-Optimization Model for Conjunctive Management of Surface Water and Groundwater for Agricultural Use

The conjunctive management of surface water and groundwater resources is essential to sustainably manage water resources. The target study is the Osan watershed, in which approximately 60–70% of rainfall occurs during the summer monsoon in Central South Korea. Surface water resources are overexploited six times as much as groundwater resources in this region, leading to increasing pressure to satisfy the region’s growing agricultural water demand. Therefore, a simulation-optimization (S-O) model at the sub-basin scale is required to optimize water resource allocation in the Osan watershed. An S-O model based on an artificial neural network (ANN) model coupled with Jaya algorithm optimization (JA) was used to determine the yearly conjunctive supply of agricultural water. The objective was to minimize the water deficit in the watershed subject to constraints on the cumulative drawdown in each subarea. The ANN model could predict the behaviour of the groundwater level and facilitate decision making. The S-O model could minimize the water deficit by approximately 80% in response to the gross water demand, thereby proving to be suitable for a conjunctive management model for water resource management and planning.