Complex processes govern spatiotemporal distribution of precipitation within the high-mountainous headwater regions (commonly known as the upper Indus basin (UIB)), of the Indus River basin of Pakistan. Reliable precipitation simulations particularly over the UIB present a major scientific challenge due to regional complexity and inadequate observational coverage. Here, we present a statistical downscaling approach to model observed precipitation of the entire Indus basin, with a focus on UIB within available data constraints. Taking advantage of recent high altitude (HA) observatories, we perform precipitation regionalization using K-means cluster analysis to demonstrate effectiveness of low-altitude stations to provide useful precipitation inferences over more uncertain and hydrologically important HA of the UIB. We further employ generalized linear models (GLM) with gamma and Tweedie distributions to identify major dynamic and thermodynamic drivers from a reanalysis dataset within a robust cross-validation framework that explain observed spatiotemporal precipitation patterns across the Indus basin. Final statistical models demonstrate higher predictability to resolve precipitation variability over wetter southern Himalayans and different lower Indus regions, by mainly using different dynamic predictors. The modeling framework also shows an adequate performance over more complex and uncertain trans-Himalayans and the northwestern regions of the UIB, particularly during the seasons dominated by the westerly circulations. However, the cryosphere-dominated trans-Himalayan regions, which largely govern the basin hydrology, require relatively complex models that contain dynamic and thermodynamic circulations. We also analyzed relevant atmospheric circulations during precipitation anomalies over the UIB, to evaluate physical consistency of the statistical models, as an additional measure of reliability. Overall, our results suggest that such circulation-based statistical downscaling has the potential to improve our understanding towards distinct features of the regional-scale precipitation across the upper and lower Indus basin. Such understanding should help to assess the response of this complex, data-scarce, and climate-sensitive river basin amid future climatic changes, to serve communal and scientific interests.
The high-altitude Indus basin is one of the most complex and inadequately explored mountain terrains in the World, where reliable observations of precipitation are highly lacking. Therefore, spatially distributed precipitation products developed at global/regional scale are often used in several scientific disciplines. However, large uncertainties in precipitation estimates of such precipitation data sets often lead to suboptimal outcomes. In this study, performance of 27 widely used gridded precipitation products belonging to three different categories of gauge-based, reanalysis and merged products is evaluated with respect to high-quality reference climatologies of mean monthly precipitation. Widely used statistical measures and quantitative analysis techniques are used to analyse the spatial patterns and quantitative distribution of mean monthly, seasonal and annual precipitation at sub-regional scale.Mean annual precipitation estimates of the gridded data sets are cross validated with the corresponding adjusted streamflows using Turc-Budyko nondimensional analysis. Results reveal poor to moderately good performance of the gridded data sets. Marked differences in spatiotemporal and quantitative distribution of precipitation are found among the data sets. All data sets are consistent in their patterns showing negative or dry bias in wet areas and
Underperformance of the irrigation systems and poor cost recovery from irrigated area in Pakistan have been a source of concern for the last few decades and since then it has been the subject of considerable external assistance and internal policy reforms. To address these problems in the management of irrigation systems, the World Bank proposed a number of institutional changes for irrigation management turnover (IMT). After thorough consideration it was decided to decentralize instead of privatizing the irrigation system management and to promote farmers' participation in the system management. Under these reforms, management at secondary canal level has recently been handed over to the farmers' organizations (FOs) of selected distributaries at a pilot scale.This study was designed to evaluate the farmer-managed distributary in southern Punjab. Initial field measurements revealed that hydraulic aspects of the irrigation service delivered by the FO management have been significantly improved and as a result a highly proportionate and equitable water distribution pattern was observed, particularly at the tail reaches of the distributary during the post-transfer scenario. Due to effective FO management farmers' interventions to increase the outlet discharge by illegal means have almost ceased. As a result of these improvements made by the FO in system management the extent of irrigated area has on average increased by 6-7% even under severe drought and continued famine-like conditions prevailing in the country during recent years. Most importantly, cost recoveries have increased by an amount of 14% for summer and 23% for winter growing seasons respectively from the irrigated area of the distributary. Thus experience from the Hakra 4-R distributary has shown that even under undesirable natural circumstances IMT was quite effective in achieving the key targets of the institutional reforms launched at pilot scale in the country. quelques canaux secondaires. En raison de ces améliorations dans la gestion de système la superficie irriguée a augmenté avec 6 à 7% même pendant la sécheresse et la periode de famine régnant dans le pays pendant des années récentes. La recouvrement des coûts a été augmenté de 14% pendant l'été et de 23% pendant les saisons des cultures d'hiver. Ainsi l'expérience de Hakra 4-R distributary a prouvé que même sous des conditions difficiles le transfert de gestion de l'irrigation était efficace dans la realisation des objectifs clés des réformes institutionnelles lancées à la échelle pilote dans le pays.
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