Your search found 4 records
1 Sreelash, K.; Buis, S.; Sekhar, M.; Ruiz, L.; Tomer, S. K.; Guerif, M. 2017. Estimation of available water capacity components of two-layered soils using crop model inversion: effect of crop type and water regime. Journal of Hydrology, 546:166-178. [doi: https://doi.org/10.1016/j.jhydrol.2016.12.049]
Water holding capacity ; Water availability ; Estimation ; Soil water content ; Soil hydraulic properties ; Layered soils ; Soil moisture ; Field capacity ; Wilting point ; Water stress ; Crop management ; Models ; Sensitivity analysis ; Leaf Area Index ; Maize ; Sorghum ; Sunflowers ; Turmeric ; Remote sensing ; Catchment areas / South India / Berambadi Catchment
(Location: IWMI HQ Call no: e-copy only Record No: H048041)
(1.43 MB)
Characterization of the soil water reservoir is critical for understanding the interactions between crops and their environment and the impacts of land use and environmental changes on the hydrology of agricultural catchments especially in tropical context. Recent studies have shown that inversion of crop models is a powerful tool for retrieving information on root zone properties. Increasing availability of remotely sensed soil and vegetation observations makes it well suited for large scale applications. The potential of this methodology has however never been properly evaluated on extensive experimental datasets and previous studies suggested that the quality of estimation of soil hydraulic properties may vary depending on agro-environmental situations. The objective of this study was to evaluate this approach on an extensive field experiment. The dataset covered four crops (sunflower, sorghum, turmeric, maize) grown on different soils and several years in South India. The components of AWC (available water capacity) namely soil water content at field capacity and wilting point, and soil depth of two-layered soils were estimated by inversion of the crop model STICS with the GLUE (generalized likelihood uncertainty estimation) approach using observations of surface soil moisture (SSM; typically from 0 to 10 cm deep) and leaf area index (LAI), which are attainable from radar remote sensing in tropical regions with frequent cloudy conditions. The results showed that the quality of parameter estimation largely depends on the hydric regime and its interaction with crop type. A mean relative absolute error of 5% for field capacity of surface layer, 10% for field capacity of root zone, 15% for wilting point of surface layer and root zone, and 20% for soil depth can be obtained in favorable conditions. A few observations of SSM (during wet and dry soil moisture periods) and LAI (within water stress periods) were sufficient to significantly improve the estimation of AWC components. These results show the potential of crop model inversion for estimating the AWC components of two-layered soils and may guide the sampling of representative years and fields to use this technique for mapping soil properties that are relevant for distributed hydrological modelling.
2 Baccar, M.; Bergez, J.-E.; Couture, S.; Sekhar, M.; Ruiz, L.; Leenhardt, D. 2021. Building climate change adaptation scenarios with stakeholders for water management: a hybrid approach adapted to the South Indian water crisis. Sustainability, 13(15):8459. [doi: https://doi.org/10.3390/su13158459]
Climate change adaptation ; Stakeholders ; Water management ; Participatory approaches ; Farming systems ; Natural resources management ; Groundwater recharge ; Water levels ; Drip irrigation ; Pumping ; Infrastructure ; Farm ponds ; Rainfed farming ; Socioeconomic development ; Nongovernmental organizations ; Sustainability ; Policies / India / Berambadi Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H050560)
(2.96 MB) (2.96 MB)
Climate change threatens the sustainability of agriculture and natural resources. Adaptive solutions must be designed locally with stakeholders. We developed the Approach for Building Adaptation Scenarios with Stakeholders (ABASS), which aims to identify adaptation policies and corresponding scenarios of natural resource management in the context of climate change. Its originality is the combination of different existing participatory methods, organized in three phases. In step 1, experts identify local environmental problems on a map and build the assumption tree of local climate change effects. In step 2, experts identify stakeholders. Step 3 leads to the construction of adaptation scenarios with stakeholders in two phases. First, in a participatory workshop gathering numerous stakeholders, the assumption tree is presented to help stakeholders identify potential policies that address the effects of climate change. Then, using the map produced in step 1, each group of stakeholders separately translates each potential policy into a detailed scenario. We applied ABASS to the context of groundwater overexploitation in South India. Two policies at the farm level emerged as consensual: (i) ponds to harvest runoff water and (ii) drip irrigation to conserve water; but their implementation highlights the differences of opinion among stakeholders.
3 Verma, K.; Manisha, M.; Santrupt, R. M.; Anirudha, T. P.; Goswami, S.; Sekhar, M.; Ramesh, N.; Kumar, M. S. M.; Chanakya, H. N.; Rao, L. 2023. Assessing groundwater recharge rates, water quality changes, and agricultural impacts of large-scale water recycling. Science of The Total Environment, 877:162869. [doi: https://doi.org/10.1016/j.scitotenv.2023.162869]
Groundwater recharge ; Water quality ; Semiarid zones ; Wastewater treatment ; Water reuse ; Freshwater ; Land use ; Land cover ; Precipitation ; Infiltration ; Soil types ; Aquifers ; Agricultural productivity / India / Karnataka / Kolar
(Location: IWMI HQ Call no: e-copy only Record No: H051877)
(6.08 MB)
The over-exploitation and insufficient replenishment of groundwater (GW) have resulted in a pressing need to conserve freshwater and reuse of treated wastewater. To address this issue, the Government of Karnataka launched a large-scale recycling (440 million liters/day) scheme to indirectly recharge GW using secondary treated municipal wastewater (STW) in drought-prone areas of Kolar district in southern India. This recycling employs soil aquifer treatment (SAT) technology, which involves filling surface run-off tanks with STW that intentionally infiltrate and recharge aquifers. This study quantifies the impact of STW recycling on GW recharge rates, levels, and quality in the crystalline aquifers of peninsular India. The study area is characterized by hard rock aquifers with fractured gneiss, granites, schists, and highly fractured weathered rocks. The agricultural impacts of the improved GW table are also quantified by comparing areas receiving STW to those not receiving it, and changes before and after STW recycling were measured. The AMBHAS_1D model was used to estimate the recharge rates and showed a tenfold increase in daily recharge rates, resulting in a significant increase in the GW levels. The results indicate that the surface water in the rejuvenated tanks meets the country's stringent water discharge standards for STW. The GW levels of the studied boreholes increased by 58–73 %, and the GW quality improved significantly, turning hard water into soft water. Land use land cover studies confirmed an increase in the number of water bodies, trees, and cultivated land. The availability of GW significantly improved agricultural productivity (11–42 %), milk productivity (33 %), and fish productivity (341 %). The study's outcomes are expected to serve as a role model for the rest of Indian metro cities and demonstrate the potential of reusing STW to achieve a circular economy and a water-resilient system.
4 Baccar, M.; Raynal, H.; Sekhar, M.; Bergez, J.-E.; Willaume, M.; Casel, P.; Giriraj, P.; Murthy, S.; Ruiz, L. 2023. Dynamics of crop category choices reveal strategies and tactics used by smallholder farmers in India to cope with unreliable water availability. Agricultural Systems, 211:103744. [doi: https://doi.org/10.1016/j.agsy.2023.103744]
Water availability ; Smallholders ; Farmers ; Cropping patterns ; Diversification ; Farming systems ; Groundwater irrigation ; Sequence analysis ; Water resources ; Groundwater table ; Water requirements ; Rainfall ; Decision making ; Resilience ; Socioeconomic aspects / India / Berambadi Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H052188)
(5.85 MB)
CONTEXT: Changing cropping pattern is a potentially effective lever to cope with unreliable water resources, but given the multiple factors driving crop choices, assessing if farmers actually use it specifically for this objective remains difficult.
OBJECTIVE: We aimed at analyzing whether and how farmers choose crop categories with different water requirements to cope with limited water resources in peninsular India.
METHODS :We monitored over a 10 year period crop choices, weather, and groundwater level for the three cropping seasons in 205 irrigable farms in the Berambadi watershed, in southern India. We categorized crops according to their seasonal water requirement. We built farm types based of Sequence Analysis and Agglomerative Hierarchical Clustering of crop category sequences over 10 years for each cropping season. For each type, we correlated the variation in crop category choices to variations in rainfall and groundwater availability, to identify tactical adaptations. Finally, we grouped the crop category choices of the three seasons to identify the main strategic pathways followed by farmers.
RESULTS AND CONCLUSIONS: Sequence analysis of crop category choices revealed different types of crop category sequences, reflecting farmers' different strategies, which were not significantly linked with groundwater availability. We identified five main pathways across the three cropping seasons, including combining long-cycle irrigated crop and other crop categories, specializing in short-cycle irrigated crops over two or three seasons, specializing in rainfed crops or abandoning agriculture. Within each type, correlations between variation in water availability and crop categories highlighted specific tactical adaptations.
SIGNIFICANCE: The opportunity for farmers to choose their crops among a variety of species encompassing a large range of water requirements allows them to base their system resilience on a large diversity of strategies and tactics. This suggests that some farmers empirically estimate the water balance of their cropping systems at seasonal scale to take tactical decisions. Providing them with science-based tools to refine this estimation could therefore improve their decision-making. This also implies that modelling farmer decisions must account for their diversity. Maintaining or increasing the capacity of farmers to cultivate a broad range of crops with different seasonal water requirements is important for farming system resilience, and should therefore be part of the agenda of policy makers for agricultural or environmental regulations.
OBJECTIVE: We aimed at analyzing whether and how farmers choose crop categories with different water requirements to cope with limited water resources in peninsular India.
METHODS :We monitored over a 10 year period crop choices, weather, and groundwater level for the three cropping seasons in 205 irrigable farms in the Berambadi watershed, in southern India. We categorized crops according to their seasonal water requirement. We built farm types based of Sequence Analysis and Agglomerative Hierarchical Clustering of crop category sequences over 10 years for each cropping season. For each type, we correlated the variation in crop category choices to variations in rainfall and groundwater availability, to identify tactical adaptations. Finally, we grouped the crop category choices of the three seasons to identify the main strategic pathways followed by farmers.
RESULTS AND CONCLUSIONS: Sequence analysis of crop category choices revealed different types of crop category sequences, reflecting farmers' different strategies, which were not significantly linked with groundwater availability. We identified five main pathways across the three cropping seasons, including combining long-cycle irrigated crop and other crop categories, specializing in short-cycle irrigated crops over two or three seasons, specializing in rainfed crops or abandoning agriculture. Within each type, correlations between variation in water availability and crop categories highlighted specific tactical adaptations.
SIGNIFICANCE: The opportunity for farmers to choose their crops among a variety of species encompassing a large range of water requirements allows them to base their system resilience on a large diversity of strategies and tactics. This suggests that some farmers empirically estimate the water balance of their cropping systems at seasonal scale to take tactical decisions. Providing them with science-based tools to refine this estimation could therefore improve their decision-making. This also implies that modelling farmer decisions must account for their diversity. Maintaining or increasing the capacity of farmers to cultivate a broad range of crops with different seasonal water requirements is important for farming system resilience, and should therefore be part of the agenda of policy makers for agricultural or environmental regulations.
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