Terms Of Water Productivity Research Articles

English

This study was conducted at the Ilu Gelan district Western Shewa zone of Oromia Regional State to evaluate the impacts of furrow dimensions on yield and water productivity of onion. The experiment was laid out in a randomized complete block design with three treatments replicated four times. The experimental treatments including farmer practice or T1 (farmer practice with top width of 23 cm, bottom width of 13 cm and depth of 11 cm without determined flow rate), T2 (Furrow with top width of 45 cm, bottom width of 20 cm and depth of 12 cm with determined flow rate) and T3 (Furrow with top width of 35 cm, bottom width of 14 cm and depth of 10 cm with determined flow rate) having a plot size of 8 m × 5 m with spacing of 0.5 m × 1 m between plots and replications respectively. The highest application efficiency of (75.87%) was recorded under treatment T2 and the lowest application efficiency of (56.17%) was recorded from T1 that is, farmer practice when compared with other treatments. The highest distribution uniformity of (89%) was recorded from treatment T2 and lowest (81%) was from treatment T1. In terms of water productivity and yield of onion the highest values of 5.2 kg/m3 and 1952 kg/ha were recorded from T2 respectively. Similarly, lowest values 3.11 kg/m3 and 15088 kg/ha were obtained from T1 respectively. There were significance differences in plant height among all treatments at significance level of 5%. The highest (41.525 cm) was recorded from T2 and the lowest (39.275 cm) was obtained from T1. Further research covering all soil types is recommended to be more inclusive. Key words: Furrow irrigation, furrow dimension, grain yield, irrigation efficiency, onion, water productivity.

WATER USE EFFICIENCY IN DIFFERENT CROPS CULTIVATION: A STUDY OF BORE-WELL OWNING FARMERS FROM SOUTH INDIA

Due to increased water scarcity, many new programmes have been introduced in the recent years to increase the water use efficiency in India agriculture, which consumes over 85 percent of the available water. One important question often asked in the context of water use is whether the water is used efficiently in different crops. This study makes an attempt to estimate the water use efficiency of three water-intensive crops namely curry banana, sugarcane and paddy which are cultivated using groundwater irrigation. The study was carried out using field survey data collected from Sivagangai district of Tamil Nadu, India. Multiple regression analysis has been used to find out as to how efficiently water is used in impacting the value of output of the selected crops. The study found that irrigation water productivity and water use efficiency were higher for sugarcane crop. But, in terms of profitability and economic water productivity, curry banana crop cultivation seems to be more efficient. Sugarcane seems to be an efficient crop in terms of water productivity, but curry banana appears to be an efficient in terms of economic water productivity.

Incorporating the red jujube water footprint and economic water productivity into sustainable integrated management policy

There are nearly two million ha of red jujube in the arid inland agricultural region south of the Tianshan mountains in China that produce approximately 37.2% of the global red jujube market. This paper provides an insight into the spatiotemporal variation of the water footprint and economic water productivity of red jujube cultivation in six main red jujube-producing areas. The effects of regional policies, industrial clusters, planting structures, irrigation methods and brand values studied extensively in this paper and shows how these driving factors affect the variation. Time series data covering the period of 2003–2015 was used for the study. The results showed that the annual variation of yield, cultivated areas, water footprint and economic water productivity of red jujube cultivation have experienced upward trends in the Tianshan regions, but that there were also few differences between different growing areas. The blue water makes the largest contribution (more than 70%) to the components of the red jujube water footprint in each red jujube producing area. The contribution of grey water footprint to the total consumptive WF was quite small (less than 10%) and the remaining 10%–15% was due to the green water. The water footprint and overall economic water productivity through the red jujube in various producing areas are affected by local government management and performance. The possible ways of improving economic water productivity in terms of red jujube cultivation are through policy, technological and management interventions.

HEALTH WATER MANAGEMENT SYSTEM IN URBAN AREA

Conservation of water resources in Indonesia is based on the management of springs on a large scale or in terms of water production. The approach that is often used is management from the demand side so that the mindset of the people is still trapped that water resources are free goods that can be taken without having to renew them again. This research tries to achieve direct community participation to participate in realizing and managing water resources directly.
 Community participation techniques use advice on implementing policies to improve water resources. The policies offered include infiltration wells, biopori, and reforestation. The policy offer is the right alternative for households/communities directly. The purpose of this study is divided into 3, namely knowing the level of community WTP, knowing the variables that affect the WTP and preference analysis of alternative policy choices.
 The results of the analysis show that the WTP level of the city of Surakarta is still low, which is equal to WTP ≤ Rp. 50,000. Policy variables can influence the level of willingness to pay by 42.60% compared to other variables only able to influence by 15.95% calculated using multinomial logistic regression. The results of the Analytical Hierarchy Process (AHP) analysis show that the ranking 1 weighting is the infiltration well policy.

FIELD PERFORMANCE OF THE CAPILLARY WICK IRRIGATION (CAPILLARIGATION) SYSTEM FOR RICE-BASED CROPS

The Philippines is suffering from the devastating effect of climate change. During extreme drought periods when it is already too risky to plant rice, farmers are advised to plant vegetables and other short duration crops so as to maximize the use of limited water supply and have an alternate source of income. This study evaluated the field performance of a locally developed irrigation system designed to be as efficient as possible so as to maximize the use of the limited supply of water during such conditions and as low cost as possible so that smallholder farmers could afford to use it. The resulting prototype is a do-it-yourself type irrigation system which is almost similar in layout as that of the drip irrigation system, except that, among other things, it makes use of capillary wicks as drippers (hence called as capillarigation system) and maximizes the use of local and recycled materials. Results of field tests consistently showed that the capillarigation system outperformed the existing farmers’ irrigation practices (drip and hose) in terms of water productivity. In a field planted with green pepper (Capsicum annuum L.), the system yielded higher water productivity of 36.6 g/L as compared to the drip irrigation system (9.9 g/L). The same trend was observed when tested in another field planted with eggplants (Solanum melongena esculentum). Being able to work with unfiltered water, with very low operating pressure (15-20cm) and discharge rate (20-30mL/h), the capillarigation system offers advantages when compared with other existing irrigation methods. It however still needs more field tests so as to further evaluate its performance under various crop, field, soil, and water conditions.

Water productivity assessments for dwarf coconut by using Landsat 8 images and agrometeorological data

In the coastal areas of Northeast Brazil, coconut growers are replacing the tall varieties by the dwarf ones, following incentives for the coconut’s water market. The current study aimed to determine and analyze actual evapotranspiration (ET) and biomass production (BIO), for dwarf coconut water productivity (WP) assessments. This was done to subsidize the rational irrigation and crop management, by using Landsat 8 images together with agrometeorological data during the year 2016 in the Camocim County, coastal zone of Ceará state. The SAFER (Simple Algorithm for Evapotranspiration Retrieving) algorithm was used to retrieve ET, while for BIO estimations we applied the Monteith’s radiation use efficiency model (RUE), then the water productivity based on ET was calculated (WPET = BIO/ET). The highest ET and BIO rates, above 4.0 ± 0.6 mm d−1 and 140 ± 37 kg ha−1 d−1, respectively, happened from May to July, retrieving WPET pixel values larger than 3.5 kg m−3. It was noticed some water stress conditions, with the fraction ET to reference evapotranspiration (ET0) dropping below 0.60 from the start of August to the end of the year, affecting the WPET values. Considering also WP in terms of fruits and coconut’s water produced, it averaged 1.9 coconut fruits and 0.8 L of coconut water per cubic meter of water consumed, respectively. The results can support techniques for irrigation water storage at the palm root zones, while increasing dwarf coconut yield in Northeast Brazil.

Optimal cropping pattern design for a major distributary of Hirakud canal command in India

Gravity flow on field to field flooding basis is prevalent in most of the canal command areas in India. Furthermore, the canals being mostly unlined and at many sections ill maintained, enormous conveyance loss of water occurs causing dwindling crop production. Hirakud canal command area located in India is no exception to this predicament. Thus, augmentation of irrigation infrastructures vis-a-vis prudent crop planning is of paramount importance for increasing the overall efficiency of the canal system. This paper describes development of optimal crop planning in the Hirakud command area by considering different objectives of planning (scenarios) so that improvement in irrigation efficiency, in terms of water productivity could be feasible. Among various scenarios, the cropping pattern obtained under Scenario—II, i.e. to utilize the maximum area for cultivation, under the constraint of limiting water availability for each outlet was found to be feasible for optimal land and water utilization and generation of requisite employment. However, keeping in view the affinity of the farmers towards paddy (a heavy duty crop), Scenario—III i.e. to utilize the maximum area for cultivation with the constraints of limited irrigation water availability, and providing irrigation to heavy duty crops for at least one-third of the culturable command area of each outlet, can be adopted.

Real farm management depending on the available volume of irrigation water (part II): Analysis of crop parameters and harvest quality

The aim of MOPECO model is to maximize the gross margin of irrigated farms by a more efficient use of both the irrigable land and the irrigation water. One limitation of this model is its inability to simulate the effect of deficit irrigation on the quality of the harvests, which may affect the price perceived by the farmers. During the experiment, a farm located in Albacete (Spain) was managed by two different strategies during years 2014 and 2015. In the first strategy, the distribution of crops composed of barley, maize and onion was managed applying full irrigation (F). In the second strategy, crops were irrigated applying full irrigation or the optimized regulated deficit irrigation (O) methodology developed for MOPECO, depending on the available volume of irrigation water. The deficit levels determined by the model for reaching the maximum profitability were 0.7 of maximum evapotranspiration (ETm) for barley, and 0.9 ETm for maize and onion. The aim was to analyze the effect of the O methodology on the water productivity of the crops, on the quality of the harvests, and to determine if the O treatments would be economically penalized with regards to the F treatments due to quality drops. Hence, the O treatments reached a higher water productivity in terms of total dry biomass (average increase: 0.68kgm−3 for barley, 0.15kgm−3 for maize, and 0.01kgm−3 for onion) and dry yield (average increase: 0.26kgm−3 for barley, 0.08kgm−3 for maize, and 0.03kgm−3 for onion). The quality of the harvests and the significant differences found in this study (weight of barley and maize grains, and calibres size of bulbs in onion) did not affect the price perceived by the farmer. Due to this, the O strategy reached a higher profitability than F in the scenarios with lower availability of irrigation water (≤5000m3ha−1) (Part I). Therefore, the use of MOPECO at great scale may increase the profitability of farms located in water scarcity areas through a more efficient use of land and irrigation water.

Sustainable use of salt-degraded and abandoned farms for forage production using halophytic grasses

Four halophytic perennial forage grass species, Distichlis spicata, Paspalum vaginatum, Sporobolus virginicus and S. arabicus, were planted in three salt-degraded and abandoned farms at Mezaira’a, Madinat Zayed and Ghayathi in the United Arab Emirates. The salinity of the irrigation water in the three farms at the time of establishment of the grasses ranged between 14.1 and 17.4 dS m–1. The productivity of the grasses was assessed over 3 years (2012–14) by harvesting three times per year. Averaged over locations and species, dry biomass yields of the four grasses ranged between 32.64 and 40.68 t ha–1 year–1. Sporobolus virginicus produced highest biomass yields, followed by D. spicata, P. vaginatum and S. arabicus, although differences among the four grasses were marginal. In Madinat Zayed and Ghayathi, the average respective forage yields in terms of water productivity were estimated to be 1.68 and 2.42 kg dry matter m–3 water, better than the reported yield of the traditionally cultivated Rhodes grass (Chloris gayana) from less saline conditions. The study showed that the four halophytic grasses have the potential to contribute to rationalised use of scarce water resources for forage production, besides providing options for enhancing domestic forage production through rehabilitating the salt-affected farms that are unproductive for conventional crops.

Low cost drip irrigation: Impact on sugarcane yield, water and energy saving in semiarid tropical agro ecosystem in India

Low cost drip irrigation (LCDI) has been a recent introduction to India and it may be an inexpensive means of expanding irrigation into uncultivated areas, thereby increasing land productivity. This paper is structured into two phases. The first phase, presents an assessment of different irrigation methods (LCDI, conventional drip irrigation (CDI) with single row and paired row, siphon and flood irrigation) on sugarcane production. The results showed that cane yield and water productivity was significantly increased in both plant and ratoon crop of sugarcane owing to the methods of irrigation. Among the methods, LCDI recorded 118.6tha−1 of cane yield and it was on par with the single row CDI, which recorded the highest mean yield of 120.4tha−1 and both are found to be significantly superior to the rest of the treatments. The lowest yield was recorded in the treatment of flood irrigation (94.40tha−1). Benefit Cost Ratio analysis confirmed that LCDI performed better compared to other irrigation methods. The second phase deals with the farmer participatory research demonstrations at multi location on evaluation of LCDI with flood irrigation. LCDI out performed flood irrigation under all the locations in terms of sugarcane yield, soil moisture content, postharvest soil fertility, reduction in nutrient transport to surface and ground water, water and energy saving. These results suggest that LCDI is a feasible option to increase the sugarcane production in water scarcity areas of semiarid agro ecosystems, and have long-term sustained economic benefits than flood irrigation in terms of water productivity, energy saving and environmental sustainability.

Methodology for geomechanically controlled transmissibility through active natural fractures in reservoir simulation

Forecasting water breakthrough is a difficult task to be performed for naturally fractured reservoirs. Modeling flow through natural fractures is computationally intensive for a rigorously refined model. Hence, in many cases, it is not feasible to perform a full-field simulation considering the possibility of fracture reactivation.This work aims at applying a methodology to incorporate the flow through fractures or geomechanically active fractures in a full-field model using a commercial reservoir simulator. This is accomplished by tracking which grid blocks in a model cross the activated fractures followed by the redefinition of interblock transmissibilities. These transmissibilities are calculated using the cubic law that relates fluid flow with the fracture aperture and an average distance between crossed blocks. The methodology is well known as Embedded Discrete Fracture Model (EDFM) (Moinfar, 2013; Moinfar et al., 2014; Li et al., 2009).An in-house finite element geomechanical simulator, one-way coupled with a commercial reservoir simulator, was used to predict in-situ stresses. The classical Mohr-Coulomb failure criterion was employed to calculate fracture shear strength. The natural fracture, or a segment of the fracture, is considered permeable when the applied stress is greater than its shear strength.Various case studies indicate the efficiency and accuracy of the EDFM method in a commercial simulator. In order to demonstrate the accuracy of the method, studies were performed in five spot models, comparing the results to those with a rigorously refined fracture representation. In order to highlight the applicability of the methodology at a field-scale, three reservoir simulation case studies are presented: one comparison with the dual permeability method, one simulation of a giant field, and one simulation coupled with a geomechanical simulator. The results show that the representation of natural fractures in reservoir models may drastically change the production forecast, especially in terms of water production.

An integrated, multisensor system for the continuous monitoring of water dynamics in rice fields under different irrigation regimes.

The cultivation of rice, one of the most important staple crops worldwide, has very high water requirements. A variety of irrigation practices are applied, whose pros and cons, both in terms of water productivity and of their effects on the environment, are not completely understood yet. The continuous monitoring of irrigation and rainfall inputs, as well as of soil water dynamics, is a very important factor in the analysis of these practices. At the same time, however, it represents a challenging and costly task because of the complexity of the processes involved, of the difference in nature and magnitude of the driving variables and of the high variety of field conditions. In this paper, we present the prototype of an integrated, multisensor system for the continuous monitoring of water dynamics in rice fields under different irrigation regimes. The system consists of the following: (1) flow measurement devices for the monitoring of irrigation supply and tailwater drainage; (2) piezometers for groundwater level monitoring; (3) level gauges for monitoring the flooding depth; (4) multilevel tensiometers and moisture sensor clusters to monitor soil water status; (5) eddy covariance station for the estimation of evapotranspiration fluxes and (6) wireless transmission devices and software interface for data transfer, storage and control from remote computer. The system is modular and it is replicable in different field conditions. It was successfully applied over a 2-year period in three experimental plots in Northern Italy, each one with a different water management strategy. In the paper, we present information concerning the different instruments selected, their interconnections and their integration in a common remote control scheme. We also provide considerations and figures on the material and labour costs of the installation and management of the system.

Farm Level Water Footprints, Water Productivity and Nitrogen Use Efficiency in Irrigated Rice under Different Water and Nitrogen Management

Attempt was made to study the impact of intermittent irrigations and different nitrogen (N) doses on growth, yield, N use efficiency and water footprints of rice. A rice cultivar, ‘Lalat’ was grown with 3 water regimes in main plots (W1 = continuous flooding of 5 cm, W2 = irrigation after 2 days of water disappearance, W3 = irrigation after 5 days of water disappearance) and 5 N levels in subplots (N1=0 kg N ha−1, N2=60 kg N ha−1, N3=90 kg N ha−1, N4=120 kg N ha−1, N5=150 kg N ha−1). Among water management, lowest mean water footprint (WFP) was observed with W2 but it was at par with W1. Yield, biomass and leaf area also did not significantly differ (P> 0.05) between W1 and W2, but these were significantly lower in W3. These results suggest W2 can reduce water input without affecting rice yields. On the other hand, water productivity in terms of irrigation was higher in W3 though grain yield was less under this treatment. Among N treatments, the lowest average WFP of 1277 m3 t−1 was achieved under 150 kg N ha−1 which was at par with 120 kg N ha−1 but highest WFP of 2532 m3 t−1 was observed when no N was applied. The reduction of WFP with higher dose of N was attributed to mainly increased grain yield of rice. No significant water×nitrogen interactions on biomass, grain yield, WFP, N uptake and N use efficiency were observed.

Simulation Study of Yield and Soil Water Balance Responses of a Maize Crop to Farmers? Irrigation Scheduling Practices in Tanzania

Maize (Zea mays.L) farmers in the traditional irrigation schemes in middle Mkoji sub-catchment, Tanzania observes three irrigation scheduling practices. This paper presents a simulation study of the impacts of these scheduling practices on yield and soil water balance of the maize crop. The three scheduling practices include irrigating at 5 days and 7 days intervals throughout the crop growing season, respectively; and irrigating at 7 days interval from planting to vegetative growth stage and 5 days interval from flowering to crop maturity stages. ISIAMOD, a crop growth cum irrigation simulation model, was used to simulate grain yield, soil water balance components and crop water productivity responses for the three scheduling practices over a range of water application depths. Simulated grain yield varied from 1338 to 4023 kg/ha. Seasonal water applied and deep percolation varied from 425 to 1800 mm, and 50 to 113 mm, respectively. The crop water productivity in terms of water applied varied from 0.22 to 0.57 kg/m3. These values closely agree with field measured values reported by some researchers for the study area. Irrigating maize fields at 5 days interval throughout the crop growing season or at flowering to crop maturity gave higher water productivity output only when application depths per irrigation did not exceed 30 mm. Water application beyond this depth only led to very high deep percolation losses without appreciable difference in crop yield compared to irrigating at 7 days interval throughout the crop growing season. Moreover, the productivity of water applied dropped by about 30 and 50 %. This implies that farmers who irrigate at 5 days interval because of they have access to water do not have any advantage (in terms of yield and water productivity) over those who irrigate at 7 days interval except they minimize water applied to their fields. Water application depth for higher productivity under the 7 days irrigation interval for the maize crop in the study area was 40 to 45 mm depth. Beyond this depth, there was no appreciable increase in grain yield but a fall in productivity of applied water and a buildup of deep percolation. To avoid over irrigation and the consequences associated with it, maize farmers at any sector of the irrigation scheme in the study area are advised to observe 7-day irrigation interval and keep water application depth within 40-45 mm per irrigation.

Evaluation of Drip Irrigation Systems on Growth and Physiology of Aerobic Rice

Drip irrigation studies were conducted in aerobic rice during dry season, 2012 in Coimbatore, Tamil Nadu, India. Three levels of lateral distances (0.6 m, 0.8 m or 1.0 m) with two discharge rates (0.6 or 1.0 lph emitters) were experimented. Among two-discharge rates, 1.0 lph drippers out performed 0.6 lph drippers in terms of water productivity and grain yield. Among the lateral distances, 0.8 m lateral distance was adjudged as optimum spacing for its better performance in growth, physiological and yield attributes than rest of the lateral distances. Interactively, laterals spaced at 0.8 m with 1.0 lph drippers exhibited better performance by way of growth parameters (plant height, tiller density, root biomass and total dry matter accumulation), physiological attributes (Y w , Chlorophyll content, catalase activity and malondialdehyde content), yield and its components (productive tillers, spikelet numbers, filled grain percentage and harvest Index) along with water productivity. Therefore, it is suggested that the lateral spacing of 0.8 m with 1.0 lph drippers with the plants spaced at 20x10 cm is the best treatment for aerobic rice cultivation in enhancing the values for grain yield and water productivity in the areas of limited water availability.

Hindcasting the effects of climate change on rice yields, irrigation requirements, and water productivity

An ex post facto investigation of the effects of climate change on rice production over the past few decades will be helpful for planning future climate change. Here, a simulation study was carried out to evaluate the impacts of climate change on the yields, irrigation requirements, and water productivity of rice in Kaifeng, China from 1951 to 2010. The rice growth model ORYZA 2000 was adopted to simulate the yields and irrigation requirements (IR); then, water productivity in terms of irrigation water (WPI), evapotranspiration (WPET), and total water use (WPI+R) was calculated, and the Mann–Kendall test was employed to detect the trends in the variables. The reduction in yield was caused by the shortened GSL, increased temperature, and decreased hours of sunshine. The decreased seasonal IR resulted from both the increased rainfall and decreased ETc, while the latter played a dominate role. The WPI seemed not sensitivity to climate change, while WPET and WPI+R were strongly linked with climate change. More productive crop variety or changing the planting schedule could avoid the negative effects posed by global warming, stilling, and dimming.

A Study on Water Demand Load Estimation by Using Unit of Living Water - Focused on Micro Water Supply Area in Daegu City

Water supply capability has been significantly reduced as water demand has been increased due to changes of the world's weather, causing the increase of drought frequency, and urbanization. In terms of water production, water can be secured by construction a dam or procuring substitute water. However, the study approaches in terms of management of water supply area to control the existing water efficiently. Therefore, water demand was estimated by buildings, by which water load of micro water supply area was calculated. As a result, the deviation of water demand for 1,357 micro water supply areas could be calculated while the alternatives to dissolve the spatial demand unbalance were suggested by two types. From the study, firstly, we could anticipate the total water supply demand from the total sum by filtration plants but it was not possible to anticipate the characteristics of distribution within urban areas. For this, the study attempted to anticipate the demand of each 250 thousands of buildings, comprehending the demand of micro areas. Secondly, based on the built results, we suggest the directions to dissolve the water demand unbalance between and among regions, which could be the foundation to suggest the concrete methodology in the future.

Effects of regulated deficit irrigation and mulch on yield, water use and crop water productivity of onion in Samaru, Nigeria

This paper presents the findings of the effects of regulated deficit irrigation and mulch materials on yield, water use and water productivity of onion crop. The field experiments were conducted in 2008/09 and 2009/10 irrigation seasons at the Institute for Agricultural Research Samaru Zaria, Nigeria. Sixteen treatments comprising of four levels of water application depths (irrigating at 25, 50, 75, and 100% weekly reference evapotranspiration (WRET)) and four levels of mulching (no-mulch, using rice straws, black and white transparent polyethylene materials) were studied each season. Surface irrigation was used and the crop was planted in basins. Water applied per irrigation, soil moisture contents before and after irrigation was monitored throughout the seasons while the harvested bulb yields were weighted and graded. The bulb yields in the two seasons ranged from 6.3 to 20.6t/ha. The seasonal water applied varied from 225 to 480mm while the seasonal evapotranspiration (SET) computed from the soil moisture contents ranged from 201 to 376.3mm. Further analyses of results showed that irrigating onion at 25% of WRET reduced bulb yield by about 50%. Applying water at 50% of WRET caused a yield reduction of about 15.5–23.0%. However, irrigating onion at 75% of WRET reduced bulb yield by less than 10%. Results also revealed that seasonal evapotranspiration (SET) of the onion crop were largely influenced by the depths of water applied rather than mulching. Irrigating the onion crop at 50 and 75% of WRET gives higher water productivity in terms of water supplied for the onion crop. Mulching with rice straw or black polyethylene did significantly improve the crop water productivity of the onion crop. In order to maximize irrigation water utilization under limited water supply to improve crop water productivity in the study area, onion crop should be mulched with rice or black polyethylene and water application depth per irrigation should be kept at 50–75% weekly reference evapotranspiration.

Operation of gravity-driven ultrafiltration prototype for decentralised water supply

Abstract The study aims at assessing in long-term trials a gravity-driven ultrafiltration pilot plant designed for a capacity of 5 m3 d−1. The unit was operated in South Africa with Ogunjini surface water and was run with restricted chemical intervention or maintenance (no backflush, no aeration, no crossflow and no chemical). Under South African environmental conditions and with direct filtration of the river water and only one manual drainage of the membrane reactor every weekday, the unit could fulfil the design specification in terms of water production (5 m3 d−1) as long as the turbidity of the raw water remained in a reasonable level (up to 160 NTU), with a filtration flux typically 4–6 l h m−2 (corrected at 20°C). This value was in the same range as the lab results and was consistent with the first phase results (around 5–7 l h−1 m−2 after biosand filtration). However, the flux dropped significantly to a range of 2–4 l h−1 m−2 after a rain event resulting in a turbidity peak over several days up to...

Agricultural water productivity assessment for the Yellow River Basin

Agricultural water productivity (WP) has been recognized as an important indicator of agricultural water management. This study assesses the WP for irrigated (WPI) and rainfed (WPR) crops in the Yellow River Basin (YRB) in China. WPI and WPR are calculated for major crops (corn, wheat, rice, and soybean) using experimental, statistical and empirically estimated data. The spatial variability of WPI and WRR is analyzed with regard to water and energy factors. Results show that although irrigated corn and soybean yields are significantly higher than rainfed yields in different regions of the YRB, WPI is slightly lower than WPR for these two crops. This can be explained by the seasonal coincidence of precipitation and solar energy patterns in the YRB. However, as expected, irrigation stabilizes crop production per unit of water consumption over space. WPI and WPR vary spatially from upstream to downstream in the YRB as a result of varying climate and water supply conditions. The water factor has stronger effects on both crop yield and WP than the energy factor in the upper and middle basin, whereas energy matters more in the lower basin. Moreover, WP in terms of crop yield is compared to that in terms of agricultural GDP and the results are not consistent. This paper contributes to the WP studies by a basin context, a comparison between WPI and WPR, a comparison of WP in terms of crop yield and economic value, and insights on the water and energy factors on WP. Moreover, policy implications based on the WP analysis are provided.