2. Detailed Proposal of Class Project with Pictures

From GeoMod

Flood plain modelling and mapping provides critical information to engineers and decision-makers. It makes land planning and management cost-effective, helps predicting the possible extent of flood areas, and offers the possibility of preventing damages and monitoring flood events. The conceptual foundation of this class project is that river floodplains are regional centers of ecological organization and are one of the most vulnerable regions of the world. It is hence of utmost importance that the region and its processes are understood in the best possible manner.

Location of Floodplain around the River Floodplain

Nature of the Problem: Floodplains form along the banks of mid-order streams and larger rivers. These are low-lying areas along the sides of a river channel that have regular times of heavy waterflow to cause the river to spill over and flood the land (In the United States an average of 100 people lose their lives in floods annually, with flood damage averaging more than $2 billion). This usually occurs in early spring when the snow is melting or during times when there is an unusually large amount of rainfall concentrated in a matter of a few hours or days. The flooding of the area has a great impact on the flora and fauna that inhabit the floodplain. In recent years, humans have caused an even greater strain on the floodplains by overbuilding on this area. When the natural forces show their full fury, water has no place to go but straight to the rivers. Thus the banks overflow and cause disastrous flooding scenes.

Cross Section Profile of the River and Floodplain

Aims and Objectives The goal of this study is to integrate DEM with ancillary data available in the public domain in order to study the floodplain and how the differences in increased water flow, increased gravels and sediment in the bed and increased slope actually affect the intensity of floods and floodplains.

Progress of my Project I have done floodplain modelling using HEC-RAS and GeoRAS. So I can visually see it coming up. The only problem would be the methodology how to go about it. Since programming is new to me… I know how to do all this in GIS but in programming, it’s going to be a challenge for me. My first proposal would be make the program for flooding and see the result of flooding on floodplain by increasing the water flow. Theoretically the area flooded should be more when the water flow increases.

Increase in Area of Floodplain Inundation with increase in Water

My second step would be to increase the gravels and friction in the river bed and then study their impact on the floods and floodplains. According to my experience if gravels are added, the amount of area which is flooded would be more. However it is yet to see if this can come out in the program.

Gravels in the River Bed: A common Feature

I’ll be using two kinds of DEMs (filtered and raw DEMs) and would be running my program on both of them. According to my previous experience the aerial extent of the floodplains derived from filtered DEMs are much more than those derived from unfiltered DEMs. Many studies have revealed that on an average, about 20 percent increase in the inundated area is noticed when the filtered DEMs are used. The unfiltered DEMs might even show floodplain, over forested and residential areas while, the filtered DEM should show a much smoother representation of the depth grid of the floodplain.

Floodplain Delineated from Unfiltered DEM

Floodplain Delineated from Filtered DEM

Contribution: Flood inundation is a major natural hazard world-wide and its prediction is a significant task for planners and environmental managers. Improved procedures for quantifying uncertainty in flood inundation models and for predicting the spatial variation in flood risk have been identified as vital by most institutions and environmental organizations. Innovative uses of technology will improve the ability to predict and cope with floods. Hence my small effort would contribute to a better safety mechanism for my study area, and if used for a macro scale for US and for the global village as a whole.