scholarly journals The Use of Rainfall Variability in Flood Countermeasure Planning

2017 ◽  
Vol 3 (3) ◽  
pp. 157
Author(s):  
Iis Catur Wulan Dhari
Keyword(s):  
Rainfall Variability ◽  
Extreme Rainfall ◽  
Rainfall Pattern ◽  
Land Conversion ◽  
Rainfall Runoff ◽  
Hydraulic Analysis ◽  
Hydraulic Simulation ◽  
Level Profile ◽  
Watershed Degradation ◽  
Impacts Of Climate Change

One of the impacts of climate change is the unpredictable shifting of seasons and rainfall patterns which caused flooding. Rejoso Watershed in Pasuruan Regency is one of the watersheds that suffer from flooding almost every year due to watershed degradation characterized by land conversion and changes in the hydrological behavior including the extreme rainfall pattern. This research was aimed to investigate the effect of rainfall variability on runoff and floodwater level profile along the river channel to provide technical and non-technical recommendation for handling flood problems. The hydrological analysis was performed using HEC-HMS version 4.0 software and the hydraulic analysis was conducted using HEC-RAS version 5.0.3 software. Several variations of extreme rainfall pattern were applied in the rainfall-runoff calculation to determine the representative flood discharges that will be used as input to the hydraulic simulation for evaluating the characteristics of flood water level. The result of the research shows that rainfall with the same depth yet varies in duration and starting time generate different flood hydrographs. Rejoso River could not store flood discharge with return period of 2 years with peak discharge of 201.46 m3/s that causing overflow along the stream. The recommendation to handle flood problems is by normalization, which could reduce the overtopping at several river reaches of 4,927 m, while the combination of normalization and embankment could reduce 7,843 m from the existing river length of 12,396 m.

scholarly journals Towards a reasoned 1D river model calibration

2005 ◽  
Vol 7 (2) ◽  
pp. 91-104 ◽  
Author(s):  
Jean-Philippe Vidal ◽  
Sabine Moisan ◽  
Jean-Baptiste Faure ◽  
Denis Dartus
Keyword(s):  
Model Calibration ◽  
Expert Knowledge ◽  
Fixed Bed ◽  
Rainfall Runoff ◽  
Simulation Code ◽  
Hydraulic Simulation ◽  
Flow Equations ◽  
Knowledge Based ◽  
River Hydraulics ◽  
Knowledge Levels

Model calibration remains a critical step in numerical modelling. After many attempts to automate this task in water-related domains, questions about the actual need for calibrating physics-based models are still open. This paper proposes a framework for good model calibration practice for end-users of 1D hydraulic simulation codes. This framework includes a formalisation of objects used in 1D river hydraulics along with a generic conceptual description of the model calibration process. It was implemented within a knowledge-based system integrating a simulation code and expert knowledge about model calibration. A prototype calibration support system was then built up with a specific simulation code solving subcritical unsteady flow equations for fixed-bed rivers. The framework for model calibration is composed of three independent levels related, respectively, to the generic task, to the application domain and to the simulation code itself. The first two knowledge levels can thus easily be reused to build calibration support systems for other application domains, like 2D hydrodynamics or physics-based rainfall–runoff modelling.

scholarly journals Extreme rainfall deficits were not the cause of recurring colonial era famines of southern Indian semi-arid regions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ranjini Ray ◽  
Atreyee Bhattacharya ◽  
Gaurav Arora ◽  
Kushank Bajaj ◽  
Keyle Horton ◽  
...  
Keyword(s):  
Arid Regions ◽  
Human Impacts ◽  
Rainfall Variability ◽  
Extreme Rainfall ◽  
Southern India ◽  
Colonial Era ◽  
Regional Rainfall ◽  
Semi Arid ◽  
Rainfall Deficits

AbstractUsing information contained in the eighteenth to twentieth century British administrative documents, preserved in the National Archives of India (NAI), we present a 218-year (1729–1947 AD) record of socioeconomic disruptions and human impacts (famines) associated with ‘rain failures’ that affected the semi-arid regions (SARs) of southern India. By mapping the southern Indian famine record onto long-term spatiotemporal measures of regional rainfall variability, we demonstrate that the SARs of southern India repeatedly experienced famines when annual rainfall reduced by ~ one standard deviation (1 SD), or more, from long-term averages. In other words, ‘rain failures’ listed in the colonial documents as causes of extreme socioeconomic disruptions, food shortages and human distress (famines) in the southern Indian SARs were fluctuations in precipitation well within the normal range of regional rainfall variability and not extreme rainfall deficits (≥ 3 SD). Our study demonstrates that extreme climate events were not necessary conditions for extreme socioeconomic disruptions and human impacts rendered by the colonial era famines in peninsular India. Based on our findings, we suggest that climate change risk assessement should consider the potential impacts of more frequent low-level anomalies (e.g. 1 SD) in drought prone semi-arid regions.

SMALLHOLDER FARMER’S LIVELIHOOD DIVERSIFICATION AS A RESPONSE TO CHANGED CLIMATIC PATTERNS IN CHONGWE DISTRICT, ZAMBIA.

2020 ◽  
Vol 3 (1) ◽  
pp. 1-17
Author(s):  
Mbewe Jacqueline ◽  
Kabwe Harnadih Mubanga
Keyword(s):  
Climate Change ◽  
Smallholder Farmers ◽  
Rainfall Variability ◽  
Climatic Conditions ◽  
Theory And Practice ◽  
Farm Income ◽  
Significant Difference ◽  
Rainfall Patterns ◽  
On Farm ◽  
Impacts Of Climate Change

Purpose: Climate change affects local and global rainfall patterns and hence has a counter effect on smallholder agriculture. Impacts of climate change on agriculture are largely due to rainfall variability resulting in reduced yields due to crop-water stress and emergency of pathogens and diseases. In Zambia, climate change has been manifested through increased intensity of droughts and floods. These rainfall anomalies adversely affect agriculture and food systems. In order to survive the impacts of climate change and variability, smallholder farmers in Chongwe have adopted their livelihoods and farming systems to the new climatic patterns.Methodology: This study assessed how smallholder farmers in Chongwe District have adopted their livelihoods as a response to changed climatic conditions. It also investigated the perceptions of smallholder farmers as regards changes in aspects of their climatic conditions. Data collection involved a critical review of literature related to climate change and agriculture, observations, semi- structured interviews with 60 smallholder farmers and eight key informants. The data were analysed using multiple analysis techniques which included the descriptive statistics, One-way analysis of Variance (ANOVA), and the post-hoc Least Square Difference for pairwise comparisons of incomes from different livelihoods engaged in by smallholder farmers .The gendered comparisons of livelihood engagement was done using the chi-square test of association.Findings: The results showed that all farmers perceived occurrence of changes in climatic conditions in the light of changed rainfall patterns in that there has been uncertainty in onset of rains, short rainy season, more intermittent rainfall and increased frequency of intra-seasonal droughts. These changes have led to farmers to adopt such farming techniques as potholing in preference to oxen and tractor ploughing when farming is done on smaller pieces of land. There was a significant difference in the mean annual incomes generated from on-farm livelihoods (ZMW 3677.59; n=58) and off-farm livelihoods (ZMW 6840.91; n = 58) (p= 0.001). Farmers generated the highest income returns by engaging in casual work (ZMW 10307.69; n = 13) compared to every other livelihoods common in the area such as gardening (p=0.002), petty trade (p=0.002) and on-farm livelihoods (p=0.001).Contribution to policy, theory and practice: It was therefore concluded that diversification of income through diversified livelihoods would help smallholder farmers enhance their resilience in the face of changed climatic conditions. On-farm livelihoods should not always be the main income source for farmers as results indicated that farmers engaged in casual work generated higher incomes than those who depended on farming. It was recommended that policy direction should be towards introduction of a gender responsive credit facility that can help improve women’s engagement in off-farm income generating livelihoods, as well as encourage climate change resilience.

scholarly journals A Statistical Vertically Mixed Runoff Model for Regions Featured by Complex Runoff Generation Process

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2324
Author(s):  
Peng Lin ◽  
Pengfei Shi ◽  
Tao Yang ◽  
Chong-Yu Xu ◽  
Zhenya Li ◽  
...  
Keyword(s):  
Spatial Heterogeneity ◽  
Mixed Model ◽  
Soil Surface ◽  
Extreme Rainfall ◽  
Distributed Model ◽  
Generation Process ◽  
Efficiency Coefficient ◽  
Rainfall Runoff ◽  
Runoff Generation ◽  
Runoff Model

Hydrological models for regions characterized by complex runoff generation process been suffer from a great weakness. A delicate hydrological balance triggered by prolonged wet or dry underlying condition and variable extreme rainfall makes the rainfall-runoff process difficult to simulate with traditional models. To this end, this study develops a novel vertically mixed model for complex runoff estimation that considers both the runoff generation in excess of infiltration at soil surface and that on excess of storage capacity at subsurface. Different from traditional models, the model is first coupled through a statistical approach proposed in this study, which considers the spatial heterogeneity of water transport and runoff generation. The model has the advantage of distributed model to describe spatial heterogeneity and the merits of lumped conceptual model to conveniently and accurately forecast flood. The model is tested through comparison with other four models in three catchments in China. The Nash–Sutcliffe efficiency coefficient and the ratio of qualified results increase obviously. Results show that the model performs well in simulating various floods, providing a beneficial means to simulate floods in regions with complex runoff generation process.

scholarly journals Landscape Controls on Nutrient Export during Snowmelt and an Extreme Rainfall Runoff Event in Northern Agricultural Watersheds

2019 ◽  
Vol 48 (4) ◽  
pp. 841-849 ◽  
Author(s):  
Henry F. Wilson ◽  
Nora J. Casson ◽  
Aaron J. Glenn ◽  
Pascal Badiou ◽  
Lyle Boychuk
Keyword(s):  
Extreme Rainfall ◽  
Agricultural Watersheds ◽  
Nutrient Export ◽  
Rainfall Runoff ◽  
Runoff Event

scholarly journals Flood frequency estimation by continuous simulation under climate change (with uncertainty)

2000 ◽  
Vol 4 (3) ◽  
pp. 393-405 ◽  
Author(s):  
D. Cameron ◽  
K. Beven ◽  
P. Naden
Keyword(s):  
Climate Change ◽  
Frequency Estimation ◽  
Flood Frequency ◽  
Change Scenario ◽  
Rainfall Runoff ◽  
Catchment Scale ◽  
Continuous Simulation ◽  
Starting Point ◽  
Rainfall Model ◽  
Impacts Of Climate Change

Abstract. This paper explores the potential for assessing the impacts of climate change upon flood frequency for the gauged, upland Wye catchment at Plynlimon, Wales, UK, while taking account of uncertainty in modelling rainfall-runoff processes under current conditions. A continuous simulation methodology which uses a stochastic rainfall model to drive the rainfall-runoff model TOPMODEL is utilised. Behavioural parameter sets for both the rainfall model and TOPMODEL are identified prior to the climate change runs using the Generalised Likelihood Uncertainty Estimation (GLUE) methodology. The "medium-high" UKCIP98 climate change scenario, obtained from the HadCM2 GCM simulations, is used as a starting point for a variety of different scenarios at the catchment scale. It is demonstrated that while the scenarios have only a small impact upon the likelihood weighted flood frequency uncertainty bounds in comparison with the current condition scenario, the risk of a given discharge as an element in the distribution of T year floods is changed. This underlines the need to account explicitly for uncertainty within hydrological modelling, especially in estimating the impacts of climate change. Keywords: Climate change; Floods; Frequency; TOPMODEL

scholarly journals Improved Hydraulic Simulation of Valve Layout Effects on Post-Earthquake Restoration of a Water Distribution Network

2020 ◽  
Vol 12 (8) ◽  
pp. 3492
Author(s):  
Jeongwook Choi ◽  
Doosun Kang
Keyword(s):  
Water Distribution ◽  
Distribution Network ◽  
Water Distribution Network ◽  
Seismic Damage ◽  
Hydraulic Analysis ◽  
Hydraulic Simulation ◽  
Restoration Process ◽  
Restoration Strategies ◽  
The Impact ◽  
Pressure Driven Analysis

To restore water pipes damaged by earthquakes, it is common to block the water flow by closing the associated shut-off valves. In this process, water supply suspension in the area connected to the isolated pipes is inevitable, which decreases the serviceability of the water distribution network (WDN). In this study, we identified the impact of valve layout (i.e., number and location) on system serviceability during a seismic damage restoration process. By conducting a pressure-driven-analysis (PDA) using EPANET 3.0, a more realistic hydraulic analysis could be carried out under the seismically damaged condition. Furthermore, by considering the valve-controlled segment in the hydraulic simulation, a more realistic water suspension area was determined, and efficient seismic damage restoration strategies were identified. The developed model was implemented on a WDN to demonstrate the effect of valve layout on the post-earthquake restoration process. Finally, effective restoration strategies were suggested for the application network.

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