Morphometric Behavior of Shahzad Watershed, Lalitpur District, Uttar Pradesh, India: A Geospatial Approach

Morphometric parameters are an important aspect for understanding the hydrological and morphological behaviour of the watershed. The present study is carried out in the region of the Bundelkhand region (India) which is socio-economically backward and has a history of frequent drought hence studying the watershed characteristics with reference to morphometric analysis becomes important. The remote sensing and GIS technique has been utilized to mathematically quantify the parameters of the Shahzad watershed. The watershed is mainly fed by the Shahzad River (a tributary of Jamini River) flowing from south to north direction contributing the area of 1100 km2. The various morphometric aspect viz., linear, aerial, relief and morpho-tectonic parameters indicate that the watershed is elongated in shape and is slightly uplifted from the right side in the southern part. Moreover, the watershed experiences low dissection and low run-off discharge there by indicating less erosion in the area. The other factors like drainage density, drainage frequency, infiltration number and length of over land flow indicate that the watershed has high permeability and infiltration capacity. Through this study, it can be concluded that remote sensing and GIS can be fruitfully utilized in analysing the morphometric behaviour of the region. This helps the researcher, planner and stakeholders to establish the relationship between watershed characteristics, thereby resulting in watershed management and sustainable resource management.

Case History of the Disastrous Debris Flows of Tianmo Watershed in Bomi County, Tibet, China: Some Mitigation Suggestions

Debris flows and landslides, extensively developing and frequently occurring along Parlung Zangbo, seriously damage the Highway from Sichuan to Tiebt(G318) at Bomi County. The disastrous debris flows of the Tianmo Watershed on Sept. 4, 2007, July 25, 2010 and Sept. 4, 2010, blocked Parlung Zangbo River and produced dammed lakes, whose outburst flow made 50 m high terrace collapse at the opposite bank due to intense scouring on the foot of the terrace. As a result, the traffic was interrupted for 16 days in 2010 because that 900 m highway base was destructed and 430 m ruined. These debris flows were initiated by the glacial melting which was induced by continuous higher temperature and the following intensive rainfall, and expanded by moraines along channels and then blocked Parlung Zangbo. At the outlet of watershed,the density, velocity and peak discharge of debris flow was 2.06 t/m3, 12.7 m/s and 3334 m3/s, respectively. When the discharge at the outlet and the deposition volume into river exceeds 2125 m3/s and 126×103 m3, respectively, debris flow will completely blocked Parlung Zangbo. Moreover,if the shear stress of river flow on the foot of terrace and the inclination angel of terrace overruns 0. 377 N/m2 and 26°, respectively, the unconsolidated terrace will be eroded by outburst flow and collapse. It was strongly recommended for mitigation that identify and evade disastrous debris flows, reduce the junction angel of channels between river and watershed, build protecting wall for highway base and keep appropriate distance between highway and the edge of unconsolidated terrace.

Flood Generation Mechanisms and Potential Drivers of Flood in Wabi-Shebele River Basin, Ethiopia

Flood is a natural process generated by the interaction of various driving factors. Flood peak flows, flood frequency at different return periods, and potential driving forces are analyzed in this study. The peak flow of six gauging stations, with a catchment area ranging from 169 - 124,108 km2 and sufficient observed streamflow data, was selected to develop threshold (3rd quartile) magnitude and frequency (POTF) that occurred over ten years of records. Sixteen Potential climatic, watershed and human driving factors of floods in the study area were identified and analyzed with GIS, Pearson’s correlation, and Principal Correlation Analysis (PCA) to select the most influential factors. Eight of them (MAR, DA, BE, VS, sand, forest AGR, PD) are identified as the most significant variables in the flood formation of the basin. Moreover, mean annual rainfall (MAR), drainage area (DA), and lack of forest cover are explored as the principal driving factors for flood peak discharge in Wabi-Shebele River Basin. Finally, the study resulted in regression equations that helped plan and design different infrastructure works in the basin as ungauged catchment empirical equations to compute QMPF, Q5, Q10, Q50, and Q100 using influential climate, watershed, and human driving factors. The results of these empirical equations are also statistically accepted with a high significance correlation (R2 > 0.9).