Center for Technology Alternatives for Rural Areas, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
Environmental Sciences and Engineering Department, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India; Interdisciplinary Program in Climate Studies, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
J Environ Manage. 2022 Dec 1;323:116135. doi: 10.1016/j.jenvman.2022.116135. Epub 2022 Sep 12.
Environmental degradation in the form of water shortage and uncertainty has severely affected the food systems across the globe. Especially in India, which is dominated by rain-fed farmers, the need for sustainable water resource and its management at farm level is imperative for farming livelihoods and food security of the country. Rainwater harvesting in on-farm reservoirs (OFR) can enable crop diversification, year round cropping and seasonal vegetable cultivation in rain-fed farming systems in India. However appropriate sizing of OFR remains a serious concern especially for small and marginal farmers with limited land holdings. In this study, a novel and comprehensive simulation-optimization model was developed to determine the optimal size and utilization of OFR. The simulation consisted of water balance of soil and OFR using hydrological analysis for last 28 years, through which supplement irrigation needs and, rainwater harvesting potential was estimated. Optimal use of available water in OFR was designed using a multi-stage process wherein the model generated, compared and screened appropriate vegetable plans for Rabi cultivation. The model was simulated for different OFR sizes and the optimal size was chosen based on its economic feasibility. To demonstrate the model, a case study was simulated wherein high supplement irrigation was estimated, indicating a severe limitation in rain-fed farming. A minimum OFR size of 9.9% of the total land was required. With an increase in OFR sizes, the profits increased however, the growth rate declined as the cropping area was reduced. An OFR size of 15.5% of total land was found to be optimal which gave benefit-cost ratio and payback period of 2.4 and 6.8 years respectively. Trends in cultivation plans for different sizes of OFR was observed wherein for small OFR sizes, the model generated fewer options of cultivation plans and preferred crops with high water productivity over crops with high profitability. The proposed model is generic and applicable at multiple scales and scenarios. The model could be used by environmental decision makers, farm managers, policy makers and researchers to determine the feasibility of any water resource intervention using an ecosystem centric approach when multiple scenarios of cultivation are possible.
以水资源短缺和不确定性为形式的环境恶化严重影响了全球的粮食系统。特别是在印度，那里以雨养农民为主，因此需要在农场层面实现可持续水资源及其管理，这对农民的生计和国家的粮食安全至关重要。在农场水库（OFR）中进行雨水收集可以使作物多样化，使印度雨养农业系统实现全年种植和季节性蔬菜种植。然而，OFR 的适当规模仍然是一个严重的问题，特别是对于拥有有限土地的小农户和边际农户。在这项研究中，开发了一种新颖而全面的模拟-优化模型，以确定 OFR 的最佳规模和利用方式。该模拟通过水文分析对过去 28 年的土壤和 OFR 进行水量平衡，从而估算补充灌溉需求和雨水收集潜力。通过多阶段过程设计 OFR 中可用水的最佳利用方式，模型生成、比较和筛选了适宜的冬季蔬菜种植计划。对不同的 OFR 规模进行了模型模拟，并根据其经济可行性选择了最佳规模。为了演示该模型，进行了一个案例研究模拟，其中估计了高补充灌溉量，表明雨养农业受到严重限制。需要 9.9%的总土地作为最小 OFR 面积。随着 OFR 规模的增加，利润增加，但由于种植面积减少，增长率下降。发现 15.5%的总土地作为 OFR 规模是最优的，其效益成本比和投资回报期分别为 2.4 和 6.8 年。观察到不同 OFR 规模的种植计划趋势，其中对于小型 OFR 规模，模型生成的种植计划选项较少，优先选择高水分生产率的作物，而不是高盈利性的作物。所提出的模型是通用的，可以在多个规模和场景中应用。该模型可以由环境决策者、农场管理者、政策制定者和研究人员使用，以确定在存在多种种植方案的情况下，使用以生态系统为中心的方法进行任何水资源干预的可行性。
