The Gadap Basin has been an important provider of agricultural commodities to the Karachi metropolis for centuries. However, in recent decades it has been noted that agricultural activities in this peri‐urban area of Karachi have shown a declining trend. In view of the current scenario, this study focuses on the evaluation of irrigation water quality being used in the Gadap Basin. In order to carry out this study, Wilcox's classification methods of Na⁺% (sodium percentage) and SAR (sodium adsorption ratio) have been applied. The results comprise 13 water samples collected from various localities over a period of two decades (1997–2016), which clearly show that with the passage of time water quality has degraded badly; in particular, sodium concentration that has increased substantially especially in the vicinity of sand and gravel excavation sites. According to Na⁺% calculation during 1997, 100% of samples were suitable for irrigation whereas in 2016 it had dropped to almost 50%. Similarly, the SAR has gone down, showing degradation of irrigation water quality. Moreover, the results have also been presented using geospatial techniques. The satellite imageries discriminate the sharp decline and degradation of agricultural land (60%) in the basin during the study period 1997–2016.

中文翻译：

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卡拉奇加达普盆地近郊农业的灌溉水质量和种植面积评估：Wilcox分类和地理空间技术的应用*

几个世纪以来，加达普盆地一直是卡拉奇都会区重要的农产品供应国。但是，最近几十年来，人们注意到在卡拉奇这个郊区地区的农业活动呈下降趋势。鉴于目前的情况，本研究侧重于对加达普盆地正在使用的灌溉水质量进行评估。为了进行这项研究，Wilcox对Na ⁺的分类方法已应用％（钠百分比）和SAR（钠吸附率）。结果包括在二十年间（1997-2016年）从各个地方收集的13个水样，这些数据清楚地表明，随着时间的流逝，水质已经严重恶化。特别是钠浓度显着增加，尤其是在沙子和砾石开挖地点附近。根据Na ⁺以1997年的百分比计算，有100％的样本适合灌溉，而在2016年下降至近50％。同样，SAR下降，表明灌溉水水质下降。此外，还使用地理空间技术介绍了结果。在1997年至2016年的研究期间，卫星图像可以判别该盆地农业土地的急剧减少和退化（60％）。