ABSTRACT

Assessment of consumptive water use (CWU) and water productivity at the regional scale is important to diagnose vulnerable zones to improve water use efficiencies in cropland to achieve the sustainable development goal 6.0 prescribed by the United Nations. The present study was carried out to segregate and quantify CWU into agricultural green (CWU_g) and blue (CWU_b) water use and water productivity (AWP) on seasonal, annual, and decadal (2009–2018) scales over the Indian region using satellite remote-sensing data from geostationary and polar-orbiting platforms. A logical algorithm was used to determine partitioned water use from a combination of satellite-based estimates of key variables such as agricultural water demand (AWD), actual evapotranspiration (ET_a), and effective rainfall (ER). Satellite-based estimates of CWU were evaluated with respect to ground reference that showed underestimation of the order of 15–32% but with a strong Pearson’s correlation coefficient (r = 0.80–0.99) and coefficient of determination (R² = 0.64–0.98). The reasons for this difference and uncertainties in satellite-based inputs have been explained. The decadal mean of CWU at annual scale showed wide spatial variation over India with 84% and 16% share of CWU_g and CWU_b, respectively, in kharif season and 27% and 73%, respectively, in rabi season. A non-significant increasing trend in CWU_g,kharif (0.57%) and a decreasing trend in CWU_b,kharif (–5.18%), CWU_g,rabi (–2.81%), and CWU_b,rabi (–1.77%) were observed over 10 years. A decreasing trend in green AWP (AWP_g) (–0.18%) in kharif season reveals a lack of sustainable adoption of green water management practices while a significantly increasing trend in AWP_b (2.65%) in rabi season reveals sustainable adoption of efficient irrigation management practices over 10 years. These long-term estimates would help in smoothing out trade-offs of water use versus water productivity, reducing the vulnerability and aiding in decision-making for water savings, controlled water allocation, strategic policy formulations for water, and food security especially through sustainable management practices in rainfed agriculture.

摘要

评估区域尺度的耗水量 (CWU) 和水生产力对于诊断脆弱区域以提高农田用水效率以实现联合国规定的可持续发展目标 6.0 非常重要。本研究旨在将印度地区的季节性、年度和十年 (2009-2018) 尺度上的CWU 分为农业绿色 (CWU _g ) 和蓝色 (CWU _b ) 用水和水生产力 (AWP)并进行量化。来自地球静止和极轨平台的卫星遥感数据。使用一种逻辑算法，通过结合基于卫星的关键变量估计值来确定分区用水量，例如农业需水量 (AWD)、实际蒸散量 (ET _a) 和有效降雨量 (ER)。基于卫星的 CWU 估计是根据地面参考进行评估的，该参考显示低估了 15-32%，但具有很强的皮尔逊相关系数 ( r = 0.80-0.99) 和决定系数 ( R ² = 0.64-0.98) . 已经解释了基于卫星输入的这种差异和不确定性的原因。CWU在年尺度上的年代际平均值在印度显示出较大的空间变化，在kharif季节，CWU _g和CWU _{b 的}份额分别为84％和16％，在狂犬病季节分别为27％和73％。CWU _g,kharif (0.57%)呈不显着上升趋势，CWU _b,kharif呈下降趋势(–5.18%)、CWU _g,rabi (–2.81%) 和 CWU _b,rabi (–1.77%) 被观察到超过 10 年。kharif 季节绿色 AWP (AWP _g ) (–0.18%)的下降趋势表明绿色水管理实践缺乏可持续的采用，而狂犬病季节AWP _b (2.65%)的显着增加趋势表明可持续采用高效灌溉管理实践超过 10 年。这些长期估计将有助于平衡用水与水生产力之间的权衡，降低脆弱性，并帮助制定节水决策、控制水资源分配、制定水资源战略政策和粮食安全，尤其是通过可持续管理雨养农业的实践。