Integration of Point and Remote Sensing Data for Monitoring Surface Runoff around Madinah City, Saudi Arabia

Abstract

In response to sporadic rainy storms, the fluvial catchments in the northern, eastern and southern regimes of Medina City produce surface runoff that varies in the frequency and magnitude. The determination of the most frequently flowing catchment(s) through each precipitation event and the spatial characteristics of surface runoff still represent gaps in understanding the hydrological processes associated with flash floods in arid environments. The lack of data in particular precipitation records at reliable temporal and spatial scales is considered one of the essential constraints in understanding these issues. The integration of point precipitation records and the multi-temporal satellite imagery such as LandSat TM and the Tropical Rainfall Monitoring Mission (TRMM) helped retrieve significant surface runoff events through two decades of the last century around Madinah City. The spectral signatures of surface runoff have been clearly identified from the optical remote sensing images acquired after each precipitation event. Investigating the spectral signatures of surface runoff along with its corresponding precipitation records from both Madinah climatic station and the TRMM monthly precipitation indicated that 1) there is no specific threshold of the amount of precipitation required for developing surface runoff; 2) while Madinah climatic station provided records of precipitation on the majority of surface runoff, it did not provide records on some monitored surface runoff events; 3) the spatial distribution and magnitude of the monthly precipitation of the TRMM images of 1998 have been conformed with all surface runoff events developed in W. Al-Aqeeq; and 4) W. Al-Aqeeq is considered the most frequently flowing valley around Madinah City because it developed surface runoff in response to all the precipitation events. These results emphasize the necessity of establishing a number of climatic and gauge stations in selective locations within the drainage basins around Madinah City. This proposition can facilitate studying the various rainfall and runoff characteristics for designing proper surface water harvesting strategy.