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Flood hazard delineation in an ungauged catchment by coupling hydrologic and hydraulic models with geospatial techniques—a case study of Koraiyar basin, Tiruchirappalli City, Tamil Nadu, India

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Surendar Natarajan at National Institute of Technology Tiruchirappalli
Surendar Natarajan
Nisha Radhakrishnan at National Institute of Technology Tiruchirappalli
Nisha Radhakrishnan
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Abstract and Figures

Flooding in urban basins is a major natural catastrophe that leads to many causalities of life and property. The semi-urbanized Koraiyar River basin in Tamil Nadu has important cities like Tiruchirappalli and many towns located in it. The basin unfailingly experiences a flood event in almost every decade. It is anticipated that the basin will undergo rapid unplanned urbanization in the years to come. Such fast and erratic urban developments will only increase the risk of urban floods ultimately resulting in loss of human lives and extensive damages to property and infrastructure. The effects of urbanization can be quantified in the form of land use land cover (LULC) changes. The LULC change and its impacts on urban runoff are studied for the continuous 30-year present time period of (1986–2016) to reliably predict the anticipated impact in the future time period of (2026–2036). The analysis of land cover patterns over the years shows that urbanization is more prevalent in the northern part of the basin of the chosen study area when compared with the other regions. The extreme rainfall events that occurred in the past, and the probable future LULC changes, as well as their influence on urban runoff, are studied together in the current study. In order to minimize flood damages due to these changing land use conditions, certain preventive and protective measures have to be adopted at the earliest. There are some inevitable limitations while applying traditional measures in flood modeling studies. This investigative work considers a case study on the ungauged Koraiyar floodplains. The spatial scale risk assessment is assessed by coupling geographic information systems, remote sensing, hydrologic, and hydraulic modeling, to estimate the flood hazard probabilities in the Koraiyar basin. The maximum flood flow is generated from the Hydrologic Engineering Centre-Hydrologic Modeling System (HEC-HMS), the hydrologic model adopted in the present study. The maximum flood flow is given as input to the Hydrologic Engineering Centre-River Analysis System (HEC-RAS), an effective hydraulic model that generates water depth and flood spread area in the basin. The flood depth and hazard maps are derived for 2, 5, 10, 50, and 100-year return periods. From the analysis, it is observed that the minimum flood depth is less than 1.2 m to a maximum of 4.7 m for the 100-year return period of past to predicted future years. The simulated results show that the maximum flood depth of 4.7 m with flood hazard area of 4.32% is identified as high hazard zones from the years 1986–2036, located in the center of the basin in Tiruchirappalli city. The very high hazard flood-affected zone in the Koraiyar basin during this period is about 198.85 km². It is noticed that the very low hazard zone occupies more area in the basin for the present and future simulations of flood hazard maps. The results show that the increase in peak runoff and runoff volume is marginally varied.
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Received: 29 April 2020 /Accepted: 29 September 2020 / Published online: 8 October 2020
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Abstract Flooding in urban basins is a major natural
catastrophe that leads to many causalities of life and
property. The semi-urbanized Koraiyar River basin in
Tamil Nadu has important cities like Tiruchirappalli and
many towns located in it. The basin unfailingly experi-
ences a flood event in almost every decade. It is antic-
ipated that the basin will undergo rapid unplanned ur-
banization in the years to come. Such fast and erratic
urban developments will only increase the risk of urban
floods ultimately resulting in loss of human lives and
extensive damages to property and infrastructure. The
effects of urbanization can be quantified in the form of
land use land cover (LULC) changes. The LULC
change and its impacts on urban runoff are studied for
the continuous 30-year present time period of (1986–
2016) to reliably predict the anticipated impact in the
future time period of (2026–2036). The analysis of land
cover patterns over the years shows that urbanization is
more prevalent in the northern part of the basin of the
chosen study area when compared with the other re-
gions. The extreme rainfall events that occurred in the
past, and the probable future LULC changes, as well as
their influence on urban runoff, are studied together in
the current study. In order to minimize flood damages
due to these changing land use conditions, certain pre-
ventive and protective measures have to be adopted at
the earliest. There are some inevitable limitations while
applying traditional measures in flood modeling studies.
This investigative work considers a case study on the
ungauged Koraiyar floodplains. The spatial scale risk
assessment is assessed by coupling geographic informa-
tion systems, remote sensing, hydrologic, and hydraulic
modeling, to estimate the flood hazard probabilities in
the Koraiyar basin. The maximum flood flow is gener-
ated from the Hydrologic Engineering Centre-
Hydrologic Modeling System (HEC-HMS), the hydro-
logic model adopted in the present study. The maximum
flood flow is given as input to the Hydrologic Engineer-
ing Centre-River Analysis System (HEC-RAS), an ef-
fective hydraulic model that generates water depth and
flood spread area in the basin. The flood depth and
hazard maps are derived for 2, 5, 10, 50, and 100-year
return periods. From the analysis, it is observed that the
minimum flood depth is less than 1.2 m to a maximum
of 4.7 m for the 100-year return period of past to
predicted future years. The simulated results show that
the maximum flood depth of 4.7 m with flood hazard
area of 4.32% is identified as high hazard zones from the
years 1986–2036, located in the center of the basin in
Tiruchirappalli city. The very high hazard flood-affected
zone in the Koraiyar basin during this period is about
Environ Monit Assess (2020) 192: 689
https://doi.org/10.1007/s10661-020-08650-2
Electronic supplementary material The online version of this
article (https://doi.org/10.1007/s10661-020-08650-2) contains
supplementary material, which is available to authorized users.
S. Natarajan (*):N. Radhakrishnan
Civil Engineering Department, National Institute of Technology,
Tiruchirappalli, Tiruchirappalli, Tamil Nadu 620015, India
e-mail: surendarnatarajan86@gmail.com
e-mail: 403114052@nitt.edu
N. Radhakrishnan
e-mail: nisha@nitt.edu
Flood hazard delineation in an ungauged catchment
by coupling hydrologic and hydraulic models
with geospatial techniques—a case study of Koraiyar basin,
Tiruchirappalli City, Tamil Nadu, India
Surendar Natarajan &Nisha Radhakrishnan
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... The flooding had both environmental and manmade causes [5], but human interference with the environment can lead to more floods [12][13][14][15], resulting in tragic deaths and economic damages [16,17]. Urban flooding is a leading cause of natural disaster casualties and property loss [18]. Changes in LULC, demographic change, poor governance, food insecurity, rural-to-urban migration, industrialization, and climatological conditions, along with significant rainfall events, all increase the risk of flooding [17,[19][20][21][22][23]. ...
... Flooding is a result of changes in hydrological factors caused by urbanisation [24][25][26]. Sudden shifts in LULC and urbanisation typically increase the risk of flooding [27,24], which can result in fatalities as well as significant damage to buildings [18]. The study of land-use transitions is significant due to its profound impact on urban hydrological processes [28]. ...
... To predict flood risks and improve planning and preparation, it is important to find out and measure how changes in land use influence stream flow [32,33]. To reduce the amount of damage that caused by floods, flood control systems are strictly necessary [18,34]. Safe and effective precautions are needed to reduce urban flooding resulting from changes in land use [18]. ...
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  • Nov 2018
  • NAT HAZARDS
In Canada, approaches for hazard mapping involve using a hydraulic model to generate a flood extent map that distinguishes between inundated and non-inundated areas in a deterministic way. The authors adapt a probabilistic approach to obtain flood hazard maps by accounting for uncertainty in boundary conditions and calibration parameters of a hydrodynamic model, while considering extent, probability, and depth of inundation as important flood indicators. The Qu’Appelle River in the Canadian prairies is considered as a case study to demonstrate the benefits of a probabilistic approach to obtain flooding indicators. The probability and depth of inundation are obtained for all locations in the floodplain, and their uncertainties are evaluated. A sensitivity analysis to determine factors affecting the extent of flooding at multiple locations along the river is also carried out. Further, the criterion to distinguish between flooded and non-flooded areas is modified and its subsequent effect on the flooding indicators is also evaluated. Results show low variability in depth and probability of inundation at most locations along the floodplain. It is also observed that the influence of the roughness parameters on the flooding extents is higher in the steeper stretches of the river, compared to the flatter stretches. Another component of the presented work focusses on evaluating an existing topography-based hazard map for Canada that classifies the country into different levels based on severity of flooding, by comparing it with the probabilistic hazard map obtained in this study. The comparison indicates a good level of agreement between both maps and highlights the reliability of using the topography-based hazard map where hydraulic modeling is infeasible.
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Hydrological Modeling with Respect to Impact of Land-Use and Land-Cover Change on the Runoff Dynamics in Godavari River Basin Using the HEC-HMS Model
Article
Full-text available
  • May 2018
  • ISPRS
Hydrological modeling and the hydrological response to land-use/land-cover changes induced by human activities have gained enormous research interest over the last few decades. The study presented here analyzes the spatial and qualitative changes in the rainfall-runoff that have resulted from the land-cover changes between 1985-2014 in the Godavari River Basin using the Hydrologic Engineering Centre-Hydrologic Modeling System(HEC-HMS) model and remote sensing-GIS (geographic information system) techniques. The purpose of this paper is to analyze the dynamics of land-use/land-cover (LULC) changes for the years 1985, 1995, 2005, and 2014 for the Godavari Basin. The findings reveal an increase of 0.64% of built-up land, a decrease of 0.92% in shrubland, and an increase of 0.56% in waterbodies between 1985-2014. The LULC change detection results between the years 1985-2014 indicated a drastic change in the cropland, forest, built-up land, and water bodies among all of the other classes. The urbanization and agricultural activities are the major reasons for the increase of cropland, built-up land, and water bodies, at the expense of decreases in shrubland and forest. The study had an overall classification accuracy of 92% and an overall Kappa coefficient of 0.9. The HEC-HMS model is used to simulate the hydrology of the Godavari Basin. The analyses carried out were mainly focussed on the impact of LULC changes on the streamflow pattern. The surface runoff was simulated for the year 2014 to quantify the changes that have taken place due to changes in LULC. The observed and the simulated peak streamflow was found to be the same i.e., 56,780 m 3 /s on 9 September 2014. In the validation part, the linear regression method was used to correlate the observed and simulated streamflow data at the prominent gauge station of the Badrachalam outlet for the Godavari River Basin and give a correlation coefficient value of 0.83. It was found that the HEC-HMS model is compatible and works better for the rainfall-runoff modeling, as it takes into account the various parameters that are influencing the process. The hydrological modeling that was carried out using the HEC-HMS model has brought out the significant impact of LULCC on rainfall-runoff at the Pranhita sub-basinscale, indicating the model's ability to successfully accommodate all of the environmental and landscape variables. The study indicates that deforestation at the cost of urbanization and cropland expansions leads to decreases in the overall evapotranspiration (ET) and infiltration, with an increase in runoff. The results of the study show that the integration of remote sensing, GIS, and the hydrological model (HEC-HMS) can solve hydrological problems in a river basin.
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Floods
Book
  • Jan 1978
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Assessment of flood mitigation through riparian detention in response to a changing climate – a case study
Article
  • Aug 2018
Considering that urban areas may suffer more substantial losses than riparian farmlands during floods, diverting floodwater into riparian areas for temporal detention is expected to mitigate flood damage in downstream urban areas. In this study, an assessment has been conducted to evaluate the effect of flood mitigation through riparian detention in response to a changing climate in the Tou-Chien River basin of Taiwan. An integrated 1D–2D flow model was used to simulate the movement of flood wave in the main stream and the overbank flow inundating into the nearby lowlands. Based on the numerical simulation results, the flooding extents in the basin corresponding to different return periods of flood using existing flood prevention infrastructures were investigated. A detention strategy by lowering the levee along the riparian farmlands was proposed to avoid severe flooding in the densely populated urban areas of the basin. Research findings showed that the proposed detention measure can completely protect the downstream areas from overbank flooding when a flood having 20-yr period occurs, and can effectively alleviate the downstream flooding area from 27.4 to \(7.6\,\hbox {km}^{2}\) for a flood possessing 200-yr period.
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