TITLE:
Effects of Increasing Rainfall Depths and Impervious Areas on the Hydrologic Responses
AUTHORS:
Mosammat Mustari Khanaum, Md Saidul Borhan
KEYWORDS:
Peak Discharge, Runoff, Impervious Area, HEC-HMS, WMS
JOURNAL NAME:
Open Journal of Modern Hydrology,
Vol.13 No.2,
March
27,
2023
ABSTRACT: Hydrologic modeling is a popular tool for estimating
the hydrological response of a watershed. However, modeling processes are
becoming more complex due to land-use changes such as urbanization,
industrialization, and the expansion of agricultural activities. The primary
goal of the research was to use the HEC-HMS model to evaluate the impact of
impervious soil layers and the increase in rainfall-runoff processes on
hydrologic processes. For these purposes, the Watershed Modelling System (WMS)
and Hydrologic Engineering Center’s-Hydrologic Modeling System (HEC-HMS) models were used
in this study to simulate the rainfall-runoff process. To compute runoff rate,
runoff volume, base flow, and flow routing methods SCS curve number, SCS unit
hydrograph, recession, and loss routing methods were selected for the research,
respectively. To reduce the processing time and computational complexity, a
small section of the Pipestem Creek Watershed was selected to understand the
methods and concepts associated with the hydrologic simulation model building.
A DEM along with other required data such as land use land cover data, soil
type data, and meteorological data was utilized to delineate the watershed in
WMS. The output of WMS was utilized to run the HEC-HMS model for five different
scenario analyses. All the relevant data were plugged in to the model to get
the desired map. Subsequently, outlets at appropriate locations were selected
for the sub-basin delineation for further analysis. Finally, the model was
parametrized to get successful simulation results. Overall, peak discharges and
runoff volumes were increased with increasing storm depths and impervious
areas. Peak discharges were increased to 36% and 51% when rainfall depths were
increased by 10% and 20% from the initial rainfall depth, respectively. Runoff
volumes were also increased to 35% and 49% for the same scenarios,
respectively. Peak discharges were increased to 12% and 78% with a 10% and 20%,
respectively, increase in impervious areas. The runoff volumes were increased
by 12% and 76% when impervious areas were increased by 10% and 20%,
respectively. The simulation models responded well, and the peak discharges and
runoff volumes increased with increasing storm depths and impervious areas.