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Urbanization Impacts on Flooding in the Kansas River Basin and Evaluation of Wetlands as a Mitigation Measure
Citation:
Qaiser, K., Y. YUAN, AND R. Lopez. Urbanization Impacts on Flooding in the Kansas River Basin and Evaluation of Wetlands as a Mitigation Measure . Transactions of the ASABE. AMERICAN SOCIETY OF AGRICULTURAL AND BIOLOGICAL ENGINEERS, ST. JOSEPH, MI, 55(3):849-859, (2012).
Impact/Purpose:
Flooding is a major natural hazard which impacts different regions across the world every year. Between 2000 and 2008, from among the various types of natural hazards, floods have affected the largest number of people worldwide, averaging 99 million people per year (WDR, 2010). Within the United States from 1972 to 2006, the property losses due to a catastrophic flood (a flood causing damage of $1 million or more) event average about $80 million (Changnon, 2008) and on an average floods kill about 140 people each year (USGS, 2006). Recently in the US, the Mississippi River has experienced unprecedented flooding causing fatalities, evacuations, and large financial losses. Climate change is expected to continue enhancement of risks of extreme storm events (Milly et al., 2002) and increases in the frequency of flash floods and large-area floods in many regions are very likely to occur (Parry et al., 2007 & Alley et al., 2003). In addition, the world is also undergoing the largest wave of urbanization in history. In 2008, for the first time in history, half the world’s population resided in urban areas, and they are expected to absorb nearly all of the future population growth (UN, 2010). In the United States, there was a 34% increase in the amount of land devoted to urban and built-up uses between 1982 and 1997 (USDA, 2001). Urbanization generally increases the size and frequency of floods and may expose communities to increasing flood hazards (Parker, 2000; USGS, 2003). These developments have placed a renewed emphasis on the prediction of flood levels and damages, mainly for the purpose of disaster management and urban and regional planning (Milly et al., 2008).
Description:
This study evaluates the impacts of future land use changes on flooding in the Kansas River Basin. It also studies the impacts of wetlands on flood reduction. The study presents Hydrologic Engineering Centers-Hydrologic Modeling System (HEC-HMS) based runoff modeling and River Analysis System (HEC-RAS) based flood analysis results for SCS 100 year 24 hour design storms over the next 30 years. Land use changes in the basin mainly consist of gradual urbanization and densification from low to high intensity urban development by 2040. The models are calibrated and validated for past events and then run for future scenarios. The future land use scenarios are developed using GIS. Results show an appreciable increase in peak runoff and flood inundation extents for the various scenarios. From the present scenario to the 2040 scenario, for the different storms, there is a 15% increase in peak runoff, an average maximum 5% increase in water elevations, and an average 6.9% increase in the inundation area. Wetlands caused a considerable reduction in peak flows and inundation extents. For the different scenarios, there is an average decrease of 14% in the peak runoff, an average decrease of 8.7% in the water elevations, and an average decrease of 17.5% in the inundation area extents. This research demonstrates the importance of inlcuding wetlands in designing flood mitigation alternatives.