Water Scarce River Basin Research Articles

Blue and green water accounting for climate change adaptation in a water scarce river basin

Understanding how climate change influences the portioning of rainfall into blue water (BW) and green water (GW) is vital for establishing adaptive water management strategies in water-scarce regions. This study presents a conceptual framework to investigate climate change impacts on blue and green water accounting by integrating a hydrological model with a multi-criteria decision-making approach to prioritize watersheds for climate change adaptation. A Soil and Water Assessment Tool (SWAT) is adopted to investigate the hydrologic variability of BW and GW for baseline (1995–2019) and future (2020–2100) periods in a semi-arid Dharoi catchment of the Sabarmati River basin, India. The future climate data, derived from five general circulation models, are ensembled using a multi-model ensemble mean approach under two RCP (representative concentration pathways) scenarios. Several non-parametric tests are employed to ascertain statistically significant changes in the hydrologic variables between future and baseline periods. Further, Analytic Hierarchy Process (AHP) is applied considering seven attributes related to climate change, land use, and demographic parameters for watershed prioritization. Higher weights are assigned to the climate change attributes, followed by land use and demographic attributes. The SWAT results indicate a decrease in rainfall, BW, and GWS (green water storage) and an increase in temperature and GWF (green water flow) while traversing from the beginning of 2040 till the end of the 21st century under both RCPs. Thus, 2040 is established as a ‘tipping point’ for climate-induced changes in the Dharoi catchment, wherein a distinct reversal in the hydroclimatic regime is evident before and after 2040. Further, significant warming is observed by the end of 21st century under RCP4.5 and RCP8.5, contributing to a reduction in rainfall (up to 24.8%) and a decline in BW (up to 78.8%) across two-thirds of the watersheds in the Dharoi catchment. The AHP analysis identifies three out of ten watersheds as vulnerable and assigned ‘high priority’ for implementing adaptation measures to counter climate change-induced water scarcity.

FUNDAMENTALS OF WATER RESOURCES MANAGEMENT OF BALKASH-ALAKOL WATER BASIN

The principles of water management were developed based on the analysis of the water management situation in Balkash – Alakol water district. The analysis of modern degradation of ecological systems shows that this process is a direct result of timely forecast assessments and foresight of possible consequences of decisions taken at the stage of developing schemes for integrated use and protection of water resources for separate river basins of Kazakhstan. In water-scarce river basins, the further development of water management and, accordingly, the development of economic sectors require matching the available water resources and demand for them. Thus, ideally, it is necessary to coordinate the possibility of taking water from the environment of a certain amount of natural, including water resources, with the self-recovering ability of the environment. Due to anthropogenic activity and a sharp increase in water consumption in the upper reaches of Ile River, tense water management and ecological situation has already developed in the Balkash-Alakolskiy water basin, in which the unique Balkash lake can share the same fate as Aral Sea. The planned medium and long-term measures for development of irrigated agriculture in the territories of Zhetysu and Almaty regions result in additional excessive burden on natural environment in the region. Possible comprehensive measures are proposed to solve the strategic task of water (socio-ecological and economically optimal) management in Balkash-Alakol water basin, taking into account the preservation of Balkash Lake.

Past variations and future projection of runoff in typical basins in 10 water zones, China

Understanding the historical and future changing characteristics of key climatic variables and runoff in 10 major river zones in China is essential for water resources evaluation and management. To this end, the historical and future changing trends of key hydrometeorological variables, including precipitation, potential evapotranspiration, and runoff were analyzed in detail for each water zone across China. The climate elasticity method was also established to quantify the impacts of climate change and human activities on historical runoff variations. The results indicate that the characteristics and causes of runoff variations in China were generally spatially heterogeneous. The runoff in water-scarce river basins of northern China decreased significantly during the period of 1961-2018, variations of which were more sensitive to human activities. For southern water zones in China, the runoff showed no significant trend and climate change was the main influencing factor. On basis of 9 Coupled Model Intercomparison Project Phase 6 (CMIP6) climate model ensemble simulations under three different shared socioeconomic pathways (ssp126, ssp245 and ssp585), the future runoff in 10 typical basins of the water zones were projected and the results suggested an increasing trend of runoff over China, thanks to increasing precipitation in the rest 21 century. While under ssp585, the rising air temperature tends to evaporate more water and offset the effect of precipitation increase to some extent, resulting in that the increments of runoff under ssp585 are not necessarily greater than those under ssp245 and ssp126. Overall, our study could be used as a basis to support climate adaptation strategies and policies to cope with future water resources conditions.

Tradeoffs between Water Uses and Environmental Flows: A Hydroeconomic Analysis in the Ebro Basin

Environmental water uses and their social values have been mostly overlooked in traditional water management over the last few decades, and recently, the maintenance of environmental flows has been considered a key issue in water policies. Addressing the more sustainable management of water resources involves introducing new water allocation policies. However, these policies are often associated with tradeoffs across sectors, stakeholders, and spatial locations. This study aims to evaluate the tradeoffs and political economy aspects of allocating water among economic water uses and environmental flows in water-scarce river basins. An empirical analysis has been conducted in the Ebro River basin (Spain) as a case study, where an intense debate on the environmental flow allocation of the Ebro mouth is taking place. The study uses a hydroeconomic model that includes the major water uses in the Ebro to analyze the effects of different water allocation policies under combinations of water availability and environmental flow scenarios. The results of this study highlight the importance of assessing the opportunity costs and political implications of reallocating water from economic activities to the environment under impending climate change impacts. Moreover, the results indicate that well-functioning water allocation policies should be not only economically efficient but also socially acceptable to reduce the likelihood of failure of water reallocation to the environment.

Improved modelling of the freshwater provisioning ecosystem service in water scarce river basins

Freshwater provisioning by the landscape contributes to human well-being through water use for drinking, irrigation and other purposes. The assessment of this ecosystem service involves the quantification of water resources and the valuation of water use benefits. Models especially designed to assess ecosystem services can be used. However, they have limitations in representing the delivery of the service in water scarce river basins where water management and the temporal variability of water resource and its use are key aspects to consider. Integrating water resources management tools represents a good alternative to ecosystem services models in these river basins. We propose a modelling framework that links a rainfall-runoff model and a water allocation model which allow accounting for the specific requirements of water scarce river basins. Moreover, we develop a water tracer which rebounds the value of the service from beneficiaries to water sources, allowing the spatial mapping of the service.

Integrating Environmental Flows into Multi-Objective Reservoir Management for a Transboundary, Water-Scarce River Basin: Rio Grande/Bravo

Integrated water management seeks to balance the interests of multiple stakeholders who desire many end-uses for water within the context of institutions and regulations. This problem is particularly complex in transboundary and water-scarce basins. In the Big Bend region of the Rio Grande/Bravo, an arid, monsoonal climate combines with multiple human and environmental water demands and established treaty requirements to stress available water resources. We analyzed reservoir operation strategies in the basin to integrate environmental flow (EF) considerations into existing management objectives using a linear programming model to assess reservoir operation policies. Five potential EF regimes are evaluated for improving aquatic and riparian habitat in the Big Bend region. The model uses the historical hydrologic record of river inflows, data for flood control and bi-national water allocation requirements, and parameters for human demands and infrastructure; to compare current and optimized operations of Luis L. Leon reservoir for multiple objectives. Results indicate that alternative operational policies for monthly reservoir storage (compared to historic values) can increase EF allocations without affecting water deliveries or treaty allocations. Some tradeoffs may exist, however, in managing reservoirs for both EFs and flood control. Our approach informs management strategies for the water-stressed basin that seek to incorporate environmental goals into existing infrastructure and operations.

Adoption of irrigation water policies to guarantee water supply: A choice experiment

More efficient and sustainable use of water is increasingly becoming an urgency in drought prone parts of the world. In particular, in water scarce regions such as the Mediterranean, water supply is expected to become more uncertain because of climate change. Consequently, pro-active policy initiatives are proposed to increase supply reliability. Local context is important when the effectiveness of policies is assessed. The aim of this paper is to evaluate farmers’ acceptance of policy strategies to increase water supply reliability in the Segura, a water scarce river basin in the south-east of Spain. Results from a choice experiment suggest that farmers are willing to pay twice as much as their current irrigation water price to ensure water supply reliability through government supply guaranteed programs. However, they are averse to any institutional changes that might assist the government to achieve increased water supply.

Sustainability of national consumption from a water resources perspective: The case study for France

It has become increasingly evident that local water depletion and pollution are often closely tied to the structure of the global economy. It has been estimated that 20% of the water consumption and pollution in the world relates to the production of export goods. This study analyzes how French water resources are allocated over various purposes, and examines impacts of French production in local water resources. In addition, it analyzes the water dependency of French consumption and the sustainability of imports. The basins of the Loire, Seine, Garonne, and Escaut have been identified as priority basins where maize and industrial production are the dominant factors for the blue water scarcity. About 47% of the water footprint of French consumption is related to imported agricultural products. Cotton, sugar cane and rice are the three major crops that are identified as critical products in a number of severely water-scarce river basins: The basins of the Aral Sea and the Indus, Ganges, Guadalquivir, Guadiana, Tigris & Euphrates, Ebro, Mississippi and Murray rivers. The study shows that the analysis of the external water footprint of a nation is necessary to get a complete picture of the relation between national consumption and the use of water resources.

The downstream externalities of harvesting rainwater in semi-arid watersheds: An Indian case study

► We assess the downstream impacts of upstream rainwater harvesting in a water scarce river basin in India. ► Using data on crop water use, rainwater harvesting investments, land use, agricultural prices and production costs we simulate the impacts on cropping patterns and assess the change in agricultural value produced. ► The results indicate that upstream benefits are insufficient to compensate downstream losses and pay back investment costs when benefits are limited to a re-allocation of irrigation water. Water-related investment projects affect downstream water availability, and therefore should account for these externalities. Few projects do, however, owing to lack of awareness, lack of data and difficulty in linking upstream investments to downstream effects. This article assesses the downstream impacts of rainwater harvesting in a semi-arid basin in Southern India, focusing on the trade-offs that arise when crop water use is re-allocated from a downstream surface water irrigation system to groundwater irrigated agriculture upstream. The results indicate that the downstream impacts are considerable and that net benefits are insufficient to pay back investment costs. Further research is required to reduce the uncertainties in the water balance of irrigation systems at basin level, to account for the inter-annual variability of crop water availability and to elaborate the wider welfare effects.

Hydrological Impacts of Flood Storage and Management on Irrigation Water Abstraction in Upper Ewaso Ng’iro River Basin, Kenya

The upper Ewaso Ng’iro basin, which starts from the central highlands of Kenya and stretches northwards transcending different climatic zones, has experienced decreasing river flows for the last two decades. The Naro Moru sub-basin is used to demonstrate the looming water crisis in this water scarce river basin. The objective of the study was to show the extent of dry seasons’ irrigation water abstractions on river flows, and to assess the hydrological impact of flood storage on temporal water distribution and irrigation water management. Decreasing river flows are attributed to over-abstraction mainly for irrigating horticultural crops. The number of abstractors has increased four times over a period of 10 years. The amount of water abstracted has also increased by 64% over the last 5 years. Moreover, the proportion of unauthorized abstractions has been increasing over the years, currently at about 80% and 95% during high and low flows respectively. This has resulted in alarming conflicts among various water users. The situation is aggravated by low irrigation efficiency (25–40%) and inadequate flood storage facilities. The paper analyzes over 40 years’ observed river flow data and 5-year interval water abstraction monitoring records for 15 years. It assesses whether flood storage and management, can reduce dry seasons’ irrigation water abstractions without significantly reducing river flows to affect the sustenance of natural ecosystems downstream. The results demonstrate that flood storage and management can reduce water abstraction and increase river flows during the dry seasons, without significantly reducing high flows to affect the downstream water users. However, socio-economic, hydrological and environmental implications should be considered if a sustainable river basin water resources management strategy is to be developed and implemented. The case study of Naro Moru sub-basin is representative of the situation in the other sub-basins, and hence can be taken as a pilot basin for developing an integrated water resources management strategy that will foster socio-economic development with minimal negative hydrological impacts in the water scarce upper Ewaso Ng’iro river basin.

Land use changes and hydrological impacts related to up-scaling of rainwater harvesting and management in upper Ewaso Ng’iro river basin, Kenya

Some land use changes are driven by the need to improve agricultural production and livelihoods. Rainwater harvesting and management is one such change. It aims to retain additional runoff on agricultural lands for productive uses. This may reduce river flows for downstream users and lead to negative hydrological, socio-economic and environmental impacts in a river basin. On the other hand, rainwater storage systems may lead to positive impacts by reducing water abstractions for irrigation during dry periods. This paper presents a conceptual framework for assessing the impacts of land use changes in the upper Ewaso Ng’iro river basin in Kenya. It is based on a people–water–ecosystem nexus and presents the key issues, their interactions and how they can be addressed. The paper presents hydrological assessment of up- scaling rainwater harvesting (HASR) conceptual framework, which assesses the impacts of land use changes on hydrological regime in a river basin. The results will enhance formulation of sustainable land and water resources management policies and strategies for water-scarce river basins.

Comparison Assessment of Water Use and Damage between Modern and Traditional Rice Irrigation Schemes: Case of Usangu Basin, Tanzania

Water management and competition between users in water scarce river basins is a major challenge facing the human race. The inter dependence of users in such basins, necessitates a clear understanding of each user in relation to the location, the water demand, and the duration of water need. The understanding of these factors, together, is very important for the management of water resources in such basins without which, it is argued that, water is overused and wasted. As an example of this, the large modern and improved rice irrigation systems in Tanzania are believed to use water more efficient than the traditional irrigation systems. Yet, well-founded scientific analyses are a necessary part to quantify such beliefs as they can inform us whether the natural resource, in such systems, is properly utilized and managed or not. Likewise, such studies can allow us to quantify how much water is over used and thus the natural resource is unnecessarily degraded. This paper explores a study conducted in the Usangu basin, Tanzania, to investigate the gross and net needs for modern and traditional rice irrigation schemes, and the implications with regards to water resource management and damage. Problems relating to modernization of traditional smallholder irrigation systems and upstream--downstream water users are further discussed. The paper concludes from the study that modern irrigation schemes are inefficient compared to traditional irrigation schemes. Also modernization of traditional schemes in the study area have resulted into over abstraction and reduced productivity of water. Looking to the future, this study tells us that improvement or modernization of irrigation infrastructure should be balanced between negative impacts to available water resources albeit it's significant economic contribution to the community.

Sponge city: water balance of mega-city water use and wastewater use in Hyderabad, India

Cities are increasingly competing with agriculture for water resources as urbanization unfolds in water-scarce river basins in Asia. This study documents a partial water balance of Hyderabad city, located in the Krishna basin and currently the fastest growing city in India, and gives estimates of its impact on both traditional and wastewater irrigated area. Though previous projects have had significant local impacts on irrigated areas, additional water supply from a major reservoir on the Krishna river to Hyderabad is likely to be a relatively small component of total reservoir releases to irrigated agriculture (5.3–10.2% by 2030). Urban storm water runoff generates a volume of water of the same order of magnitude as the domestic wastewater volume, though the fate of this water vis-a `-vis irrigated agriculture is not known. Wastewater irrigation compensates for more than half of the traditional irrigated area water lost, so the urban–agriculture conflict also generates significant opportunities that also need to be considered. However, the impact of wastewater use on crop yields, cropping changes, human health and the environment need to be fully addressed. Copyright # 2005 John Wiley & Sons, Ltd.

Towards sustainable urban water resource management: a case study in Tianjin, China

AbstractSustainable water resource management has become a critical issue for the development of cities that suffer scarce water resources. Tianjin City, located in China's Huaihe basin, one of the most polluted and water‐scarce river basins in the country, is a typical example in which water is posing a major constraint to the development. This paper examines the current status of the use of water resources, and the current practices and policy measures taken for water resource management in Tianjin, with a view to drawing lessons through an evaluation of these measures. The study illustrates the role of cities and their complex interaction with their peripheries for the allocation of scarce water resources, and it suggests that a systems approach should be adopted in order to analyse and understand the complexity of the entire picture. Based on this review and evaluation of Tianjin's experience, the authors propose a framework for sustainable water resource management in cities, emphasizing the importance of taking full consideration of resource/environmental capacity and an integrated systems approach for problem solving. Copyright © 2001 John Wiley & Sons, Ltd. and ERP Environment