A remote sensing contribution to hydrologic modelling in arid and inaccessible watersheds, Pishin Lora basin, Pakistan

Abstract

AbstractThe lack of adequate field measurements often hampers the construction and calibration of rainfall‐runoff models over many of the world's watersheds. We adopted methodologies that rely heavily on readily available remote sensing datasets as viable alternatives for assessing, managing, and modelling of such remote and inadequately gauged regions. The Soil and Water Assessment Tool was selected for continuous (1998–2005) rainfall‐runoff modelling of one such area, the northeast part of the Pishin Lora basin (NEPL). Input to the model included satellite‐based Tropical Rainfall Measuring Mission precipitation data, and modelled runoff was calibrated against satellite‐based observations, the latter included: (i) monthly estimates of the water volumes impounded by the Khushdil Khan (latitude 30°40′N, longitude 67°40′E), and the Kara Lora (latitude 30°34′N, longitude 66°52′E) reservoirs, and (ii) inferred wet versus dry conditions in streams across the NEPL. Calibrations were also conducted against observed flow reported from the Burj Aziz Khan station at the NEPL outlet (latitude 30°20′N; longitude 66°35′E). Model simulations indicate that (i) average annual precipitation (1998–2005), runoff and recharge in the NEPL are 1300 × 106 m3, 148 × 106 m3, and 361 × 106 m3, respectively; (ii) within the NEPL watershed, precipitation and runoff are high for the northeast (precipitation: 194 mm/year; runoff: 38 × 106 m3/year) and northwest (134 mm/year; 26 × 106 m3/year) basins compared to the southern basin (124 mm/year; 8 × 106 m3/year); and (3) construction of delay action dams in the northeast and northwest basins could increase recharge from 361 × 106 m3/year up to 432 × 106 m3/year and achieve sustainable extraction. The adopted methodologies are not a substitute for traditional approaches, but they could provide first‐order estimates for rainfall, runoff, and recharge in the arid and semi‐arid parts of the world that are inaccessible and/or lack adequate coverage with field data. Copyright © 2011 John Wiley & Sons, Ltd.