WetSpa-Urban: An Adapted Version of WetSpa-Python, A Suitable Tool for Detailed Runoff Calculation in Urban Areas

A tool called WetSpa-Urban was developed to respond to the need for precise runoff estimations in an increasingly urbanized world. WetSpa-Urban links the catchment model WetSpa-Python to the urban drainage model Storm Water Management Model (SWMM). WetSpa-Python is an open-source, fully distributed, process-based model that accurately represents surface hydrological processes but does not simulate hydraulic structures. SWMM is a well-known open-source hydrodynamic tool that calculates pipe flow processes in an accurate manner while runoff is calculated conceptually. Merging these tools along with certain modifications, such as improving the efficiency of surface runoff calculation and simulating flow at the sub-catchment level, makes WetSpa-Urban suitable for event-based and continuous rainfall–runoff modeling for urban areas. WetSpa-Urban was applied to the Watermaelbeek catchment in Brussels, Belgium, which recently experienced rapid urbanization. The model efficiency was evaluated using different statistical methods, such as Nash–Sutcliffe efficiency and model bias. In addition, a statistical investigation, independent of time, was performed by applying the box-cox transformation to the observed and simulated values of the flow peaks. By speeding up the simulation of the hydrological processes, the performance of the surface runoff calculation increased by almost 130%. The evaluation of the simulated 10 minute flow versus the observed flow at the outlet of the catchment for 2015 reached a Nash–Sutcliffe efficiency of 0.86 and a bias equal to 0.06.

Download Full-text

Comparison of dynamic flow interaction methods between pipe system and overland in urban flood analysis

Scientific Reports ◽

10.1038/s41598-021-88246-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Xiaoli Hao ◽

Yanmin Li ◽

Shu Liu

Keyword(s):

Surface Runoff ◽

Urban Areas ◽

Goodness Of Fit ◽

Management Model ◽

Urban Flooding ◽

Dynamic Flow ◽

Urban Flood ◽

Storm Water Management Model ◽

Pipe System ◽

Flow Interactions

AbstractUrban flooding can be predicted by using different modeling approaches. This study considered different methods of modeling the dynamic flow interactions between pipe systems and surface flooding in urban areas. These approaches can be divided into two categories based on surface runoff collection units. This paper introduces a new hydrodynamic model that couples the storm water management model and the 2D overland model. The model’s efficiency was validated based on the aforementioned experimental dataset; agreement was verified by correlation values above 0.6. Additionally, this study used different approaches and compared their accuracy in predicting flooding patterns. The results show that the use of sub-catchments to model the collection of surface runoff was not predictive of the inundation process, indicating a lower goodness of fit with the recorded values than that of adopting cells. Moreover, to determine which method of adopting cells to collect runoff could better predict rainstorm-induced inundation, an error and correlation analysis was conducted. The analysis found low error and high correlation, suggesting that inundation can be effectively predicted by the new approaches. Ultimately, this study contributes to existing work on numerical analysis of the interaction methods of urban flooding.

Download Full-text

Urbanization and Changes in Cropping Patterns at Kathmandu Valley

Nepal Journal of Science and Technology ◽

10.3126/njst.v7i0.581 ◽

2007 ◽

Vol 7 ◽

pp. 113 ◽

Cited By ~ 1

Author(s):

Raj Man Shrestha

Keyword(s):

Urban Areas ◽

Cropping System ◽

Considerable Change ◽

Rapid Expansion ◽

Leafy Vegetables ◽

Kathmandu Valley ◽

Rapid Urbanization ◽

Average Growth ◽

Cropping Patterns ◽

Agriculture Land

The increase of population in Kathmandu valley is bringing a considerable change in cropping system. Rapid urbanization and introduction of new agriculture technology have encouraged the valley’s farmers to change their cropping patterns from traditional (low value crops) to new crops (high value crops). According to numerous studies made in Nepal, the change is seen considerably in winter crops than in summer crops and the land under cultivation of green leafy vegetables is increasing rapidly in the urban and semi-urban areas. An average growth of population at 3 % in the valley during the period 1951-2001 has resulted in the rapid expansion of area under urban coverage (24.6 % growth per year from 1984 - 2000) has made agriculture land of Katmandu valley to decline per year by 2.04 % (836.27 ha per year). If this trend of decline in agriculture land in Kathmandu valley continues in future too, it is expected that there will be no agriculture land left over by two and half decades in the valley. The planners should take note of this fact that if fertile land of Katmandu valley is to be preserved for agriculture necessary planning is urgently needed. <i>Nepal Journal of Science and Technology</i> Vol. 7, 2006

Download Full-text

Effects of Urban Forms on Separate Drainage Systems: A Virtual City Perspective

Water ◽

10.3390/w11040758 ◽

2019 ◽

Vol 11 (4) ◽

pp. 758 ◽

Cited By ~ 6

Author(s):

Jia ◽

Sitzenfrei ◽

Rauch ◽

Liang ◽

Liu

Keyword(s):

Urban Form ◽

Domestic Wastewater ◽

Cost Effective ◽

Three Dimensions ◽

Rapid Urbanization ◽

Drainage Systems ◽

Urban Forms ◽

Storm Water Management Model ◽

Wastewater Systems ◽

Performance Dimensions

The development of urban drainage systems is challenged by rapid urbanization; however, little attention is paid to the urban form and its effects on these systems. This study develops an integrated city-drainage model that configures typical urban forms and their associated drainage infrastructures, specifically domestic wastewater and rainwater systems, to analyze the relationship between them. Three typical types of urban forms were investigated: the square, the star, and the strip. Virtual cities were designed first, with the corresponding drainage systems generated automatically and then linked to a model herein called the Storm Water Management Model (SWMM). Evaluation was based on 200 random configurations of wastewater/rainwater systems with different structures or attributes. The results show that urban forms play more important roles on three dimensions of performance, namely economic efficiency, effectiveness, and adaptability, of the rainwater systems than of the wastewater systems. Cost is positively correlated to the effectiveness of rainwater systems among the different urban forms, while adaptability is negatively correlated to the other two performance dimensions. Regardless of the form, it is difficult for a city to make its drainage systems simultaneously cost-effective, efficient, and adaptable based on the virtual cities we investigated. This study could inspire the urban planning of both built-up and to-be-built areas to become more sustainable with their drainage infrastructure by recognizing the pros and cons of different macroscale urban forms.

Download Full-text

Where Do I Allocate My Urban Allotment Gardens? Development of a Site Selection Tool for Three Cities in Benin

Land ◽

10.3390/land10030318 ◽

2021 ◽

Vol 10 (3) ◽

pp. 318

Author(s):

B. G. J. S. Sonneveld ◽

M. D. Houessou ◽

G. J. M. van den Boom ◽

A. Aoudji

Keyword(s):

Food Insecurity ◽

Urban Agriculture ◽

Low Income ◽

Urban Areas ◽

Urban Poor ◽

Site Suitability ◽

Rapid Urbanization ◽

Middle Income ◽

Support Tool ◽

Allotment Gardens

In the context of rapid urbanization, poorer residents in cities across low- and middle-income countries increasingly experience food and nutrition deficiencies. The United Nations has highlighted urban agriculture (UA) as a viable solution to food insecurity, by empowering the urban poor to produce their own fresh foods and make some profit from surplus production. Despite its potential role in reducing poverty and food insecurity, there appears to be little political will to support urban agriculture. This is seen in unclear political mandates that are sustained by information gaps on selection criteria for UA sites. The research reported here addresses this issue in the form of a decision-making support tool that assesses the suitability of cadastral units and informal plots for allotment gardens in urban and peri-urban areas. The tool was developed and tested for three rapidly expanding cities in Benin, a low-income country in West Africa, based on an ordered logit model that relates a set of 300 expert assessments on site suitability to georeferenced information on biophysical and socio-economic characteristics. Soil, land use, groundwater depth, vicinity to market and women’s safety were significant factors in the assessment. Scaled up across all cadastral units and informal sites, the tool generated detailed baseline maps on site suitability and availability of areas. Its capacity to support policymakers in selecting appropriate sites comes to the fore by reporting changes in site suitability under scenarios of improved soil fertility and enhanced safety for women.

Download Full-text

Estimating surface runoff and groundwater recharge in an urban catchment using a water balance approach

Hydrogeology Journal ◽

10.1007/s10040-021-02385-1 ◽

2021 ◽

Vol 29 (7) ◽

pp. 2411-2428

Author(s):

Robin K. Weatherl ◽

Maria J. Henao Salgado ◽

Maximilian Ramgraber ◽

Christian Moeck ◽

Mario Schirmer

Keyword(s):

Soil Moisture ◽

Water Balance ◽

Groundwater Recharge ◽

Surface Runoff ◽

Urban Areas ◽

Water Cycle ◽

Land Use Changes ◽

Curve Number ◽

Hydrograph Separation ◽

Balance Approach

AbstractLand-use changes often have significant impact on the water cycle, including changing groundwater/surface-water interactions, modifying groundwater recharge zones, and increasing risk of contamination. Surface runoff in particular is significantly impacted by land cover. As surface runoff can act as a carrier for contaminants found at the surface, it is important to characterize runoff dynamics in anthropogenic environments. In this study, the relationship between surface runoff and groundwater recharge in urban areas is explored using a top-down water balance approach. Two empirical models were used to estimate runoff: (1) an updated, advanced method based on curve number, followed by (2) bivariate hydrograph separation. Modifications were added to each method in an attempt to better capture continuous soil-moisture processes and explicitly account for runoff from impervious surfaces. Differences between the resulting runoff estimates shed light on the complexity of the rainfall–runoff relationship, and highlight the importance of understanding soil-moisture dynamics and their control on hydro(geo)logical responses. These results were then used as input in a water balance to calculate groundwater recharge. Two approaches were used to assess the accuracy of these groundwater balance estimates: (1) comparison to calculations of groundwater recharge using the calibrated conceptual HBV Light model, and (2) comparison to groundwater recharge estimates from physically similar catchments in Switzerland that are found in the literature. In all cases, recharge is estimated at approximately 40–45% of annual precipitation. These conditions were found to closely echo those results from Swiss catchments of similar characteristics.

Download Full-text

Modelling Pluvial Flooding in Urban Areas Coupling the Models Iber and SWMM

Water ◽

10.3390/w12092647 ◽

2020 ◽

Vol 12 (9) ◽

pp. 2647

Author(s):

Esteban Sañudo ◽

Luis Cea ◽

Jerónimo Puertas

Keyword(s):

Urban Areas ◽

Flow Model ◽

Overland Flow ◽

Drainage System ◽

Urban Drainage ◽

Dynamic Link Library ◽

Storm Water Management Model ◽

Urban Street ◽

Sewer Network ◽

Overland Flow Model

Dual urban drainage models allow users to simulate pluvial urban flooding by analysing the interaction between the sewer network (minor drainage system) and the overland flow (major drainage system). This work presents a free distribution dual drainage model linking the models Iber and Storm Water Management Model (SWMM), which are a 2D overland flow model and a 1D sewer network model, respectively. The linking methodology consists in a step by step calling process from Iber to a Dynamic-link Library (DLL) that contains the functions in which the SWMM code is split. The work involves the validation of the model in a simplified urban street, in a full-scale urban drainage physical model and in a real urban settlement. The three study cases have been carefully chosen to show and validate the main capabilities of the model. Therefore, the model is developed as a tool that considers the main hydrological and hydraulic processes during a rainfall event in an urban basin, allowing the user to plan, evaluate and design new or existing urban drainage systems in a realistic way.

Download Full-text

Long-term effects of land use/land cover change on surface runoff in urban areas of Beijing, China

Journal of Applied Remote Sensing ◽

10.1117/1.jrs.8.084596 ◽

2013 ◽

Vol 8 (1) ◽

pp. 084596 ◽

Cited By ~ 16

Author(s):

Zhongchang Sun ◽

Xinwu Li ◽

Wenxue Fu ◽

Yingkui Li ◽

Dongsheng Tang

Keyword(s):

Land Use ◽

Land Cover ◽

Land Cover Change ◽

Surface Runoff ◽

Urban Areas ◽

Land Use Land Cover ◽

Long Term Effects ◽

Effects Of Land Use ◽

Beijing China

Download Full-text

Evaluation of the Main Function of Low Impact Development Based on Rainfall Events

Water ◽

10.3390/w12082231 ◽

2020 ◽

Vol 12 (8) ◽

pp. 2231

Author(s):

Meiyan Feng ◽

Kwansue Jung ◽

Fengping Li ◽

Hongyan Li ◽

Joo-Cheol Kim

Keyword(s):

Low Impact Development ◽

Hydrological Process ◽

Main Function ◽

Storm Events ◽

Rapid Urbanization ◽

Rainfall Events ◽

Hydrological Balance ◽

Storm Water Management Model ◽

Cycle System ◽

Positive Effect

Low Impact Development (LID) is one of the sustainable approaches to urban stormwater management in areas with rapid urbanization. Although LID has been shown to have a positive effect in flood reduction, the hydrological balance regulation effect of LID under a variety of rainfall events is not fully understood. In this study, we assessed the hydrological efficiency of LID at two residential–commercial mixed sites in Korea to investigate the main function of LID in terms of diverse rainfall characteristics. Storm Water Management Model (SWMM) was constructed to simulate the hydrological process numerical simulations in the pre-development, post-development and LID design scenarios, respectively. The model was calibrated and validated by using five observed rainfall–runoff events. Then, four single and four multiple LID practices (LIDs) were used to estimate their effectiveness under seven different designed rainfall events. The results indicate that LIDs substantially influence the hydrology cycle system, while the regulating effect varies with rainfall amounts. The efficiency of LIDs in flood reduction is proved to be more effective during lower storm events. However, LIDs should be designed to primarily prioritize the restoration of hydrological balance when the rainfall return period is longer.

Download Full-text

Spatial and temporal variability of rainfall and their effects on hydrological response in urban areas – a review

Hydrology and Earth System Sciences ◽

10.5194/hess-21-3859-2017 ◽

2017 ◽

Vol 21 (7) ◽

pp. 3859-3878 ◽

Cited By ~ 69

Author(s):

Elena Cristiano ◽

Marie-Claire ten Veldhuis ◽

Nick van de Giesen

Keyword(s):

Temporal Variability ◽

Urban Areas ◽

Rainfall Variability ◽

Urban Environments ◽

Hydrological Processes ◽

Small Scale ◽

Spatial And Temporal Variability ◽

Hydrological Response ◽

Weather Radars ◽

New Instruments

Abstract. In urban areas, hydrological processes are characterized by high variability in space and time, making them sensitive to small-scale temporal and spatial rainfall variability. In the last decades new instruments, techniques, and methods have been developed to capture rainfall and hydrological processes at high resolution. Weather radars have been introduced to estimate high spatial and temporal rainfall variability. At the same time, new models have been proposed to reproduce hydrological response, based on small-scale representation of urban catchment spatial variability. Despite these efforts, interactions between rainfall variability, catchment heterogeneity, and hydrological response remain poorly understood. This paper presents a review of our current understanding of hydrological processes in urban environments as reported in the literature, focusing on their spatial and temporal variability aspects. We review recent findings on the effects of rainfall variability on hydrological response and identify gaps where knowledge needs to be further developed to improve our understanding of and capability to predict urban hydrological response.

Download Full-text

Effectiveness of low-impact development for urban inundation risk mitigation under different scenarios: a case study in Shenzhen, China

Natural Hazards and Earth System Science ◽

10.5194/nhess-18-2525-2018 ◽

2018 ◽

Vol 18 (9) ◽

pp. 2525-2536 ◽

Cited By ~ 16

Author(s):

Jiansheng Wu ◽

Rui Yang ◽

Jing Song

Keyword(s):

Local Governments ◽

Risk Mitigation ◽

Low Impact Development ◽

Green Roofs ◽

Rapid Urbanization ◽

Storm Water Management Model ◽

Inundation Depth ◽

High Hazard ◽

Hazard Level ◽

Hazard Levels

Abstract. The increase in impervious surfaces associated with rapid urbanization is one of the main causes of urban inundation. Low-impact development (LID) practices have been studied for mitigation of urban inundation. This study used a hydrodynamic inundation model, coupling SWMM (Storm Water Management Model) and IFMS-Urban (Integrated Flood Modelling System–Urban), to assess the effectiveness of LID under different scenarios and at different hazard levels. The results showed that LID practices can effectively reduce urban inundation. The maximum inundation depth was reduced by 3 %–29 %, average inundation areas were reduced by 7 %–55 %, and average inundation time was reduced by 0 %–43 % under the eight scenarios. The effectiveness of LID practices differed for the three hazard levels, with better mitigation of urban inundation at a low hazard level than at a high hazard level. Permeable pavement (PP) mitigated urban inundation better than green roofs (GRs) under the different scenarios and at different hazard levels. We found that more implementation area with LID was not necessarily more efficient, and the scenario of 10 % PP+10 % GR was more efficient for the study area than other scenarios. The results of this study can be used by local governments to provide suggestions for urban inundation control, disaster reduction, and urban renewal.

Download Full-text