Comparison of digital terrain and field-based channel derivation methods in a subalpine catchment, Front Range, Colorado

2012 Summer.Includes bibliographical references.Understanding the reliability of digitally derived channel networks for mountainous headwater catchments is important to many water resource and land-use management applications. Digital elevation models (DEMs) have become an essential tool for an increasing array of mountain runoff analyses. The purpose of this study is to investigate the influence of digitally-derived topographic variables on channel network formation for a high-elevation glaciated watershed. To accomplish this, our objectives were to (1) test how differences in gridded DEM resolution affect spatially distributed topographic parameters of local slope (tan β), specific contributing area (αs), and topographic wetness index (TWI) derived from both eight and infinite directional flow algorithms, (2) map the actual stream channel network at Loch Vale and examine the influence of surface variables on channel initiation, and (3) evaluate the performance of common methods for deriving channel networks from gridded topographic data by comparing to the observed network. We found that coarser DEM resolution leads to a loss of detail in spatial patterns of topographic parameters and an increase in the calculated mean values of ln(αs) and TWI. Grid cell sizes above 1m result in a substantial shift in the overall cumulative frequency distributions of ln(αs) and TWI towards higher values. A field survey at Loch Vale revealed a complex and disjointed channel network, with 242 channelized points and 30 channel heads. We found no predictable relationships between channel head locations and geomorphic process domains. Analysis of variance (ANOVA) showed no statistically significant difference in mean ln(αs) and TWI for channel head locations grouped by elevation, aspect, slope, formation process or upslope land cover type. For most DEM resolutions and flow partitioning algorithms, deriving channel networks with spatially constant flow accumulation and TWI thresholds provides poor network representation. The publicly available National Hydrography Dataset (NHD) layer oversimplifies the channel network by neglecting almost all first and second order channels. Many of the DEM-derived channel networks that use spatially constant flow accumulation and TWI thresholds also do not reproduce the locations of low order channels in the observed channel network well. Assumptions of topographic control on channel initiation are not shown to be valid at Loch Vale, likely due to their inability to capture subsurface processes and geologic features important to channel formation. However, if using these topographically dependent threshold methods to delineate channel networks, we suggest the use of field-based survey data to identify appropriate thresholds. With appropriate thresholds, both 1m and 10m DEMs can produce channel networks with similar drainage densities to the observed network, even if locations of low order channels are not predicted accurately. Performance degrades for 30m DEMs, so we suggest that DEMs with resolutions coarser than 10m should be avoided for channel network delineation

Fluvial and tectonic geomorphology of orogenic plateaux

Geomorphology is an expression of processes acting upon an area. The links between driving processes and the resulting geomorphology are far from being fully understood. This thesis investigates controls on the dynamics and behaviour of fluvial systems from the interior of orogenic plateaux to the tectonically active plateaux margins. Orogenic plateaux provide a good study area by juxtaposing different tectonic and climatic settings that are served by the same sediment transport systems, allowing for observation of different variables on the same or similar fluvial systems. This is the first time that rivers draining orogenic plateaux have been extensively investigated. The Turkish-Iranian and Tibetan plateaux are the study areas. Forms of rivers draining from plateaux interiors, through the plateaux margins are analysed, along with alluvial fans within both the plateaux interior and plateaux margins. Plateau draining rivers act as the major route for material leaving the plateau region and a first-order control on erosive processes retarding plateau growth. Alluvial fans redistribute material within the plateau interior, enhancing the low relief topography diagnostic of a plateau. It is found that rivers draining plateaux show a sigmoidal form associated with the edge of the plateaux. High gradients and curvatures occur within the mountain ranges at the plateaux margins, while low values are present within the plateau interiors. Modelling work demonstrates that such forms to be likely responses for all plateau-draining rivers, but are most sensitive to the effects of precipitation upon a river’s ability to incise in-to the underlying sedimentary cover and bedrock lithologies. Alluvial fans in orogenic plateau regions are larger and with a lower surface gradient within the plateau interior than those nearer the active tectonic margins. It is theorised that this is due to the lack of lateral control on the accommodation space of alluvial fans within the plateau interior

Uncertainties in the Hydrological Modelling Using Remote Sensing Data over the Himalayan Region

Himalayas the “roof of the world” are the source of water supply for major South Asian Rivers and fulfill the demand of almost one sixth of world’s humanity. Hydrological modeling poses a big challenge for Himalayan River Basins due to complex topography, climatology and lack of quality input data. In this study, hydrological uncertainties arising due to remotely sensed inputs, input resolution and model structure has been highlighted for a Himalayan Gandak River Basin. Firstly, spatial input DEM (Digital Elevation Model) from two sources SRTM (Shuttle Radar Topography Mission) and ASTER (Advanced Space borne Thermal Emission and Reflection Radiometer) with resolutions 30m, 90m and 30m respectively has been evaluated for their delineation accuracy. The result reveals that SRTM 90m has best performance in terms of least area delineation error (13239.28 km2) and least stream network delineation error. The daily satellite precipitation estimates TRMM 3B42 V7 (Tropical Rainfall Monitoring Mission) and CMORPH (Climate Prediction Center MORPHing Technique) are evaluated for their feasibly over these terrains. Evaluation based on various scores related to visual verification method, Yes/no dichotomous, and continuous variable verification method reveal that TRMM 3B42 V7 has better scores than CMORPH. The effect of DEM resolution on the SWAT (Soil Water Assessment Tool) model outputs has been demonstrated using sixteen DEM grid sizes (40m-1000m). The analysis reveals that sediment and flow are greatly affected by the DEM resolutions (for DEMs>300m). The amount of total nitrogen (TN) and total phosphorous (TP) are found affected via slope and volume of flow for DEM grid size ≥150m. The T-test results are significant for SWAT outputs for grid size >500m at a yearly time step. The SWAT model is accessed for uncertainty during various hydrological processes modeling with different setups/structure. The results reflects that the use of elevation band modeling routine (with six to eight elevation bands) improves the streamflow statistics and water budgets from upstream to downstream gauging sites. Also, the SWAT model represents a consistent pattern of spatiotemporal snow cover dynamics when compared with MODIS data. At the end, the uncertainty in the stream flow simulation for TRMM 3B42 V7 for various rainfall intensity has been accessed with the statistics Percentage Bias (PBIAS) and RSR (RMSE-observations Standard Deviation Ratio). The results found that TRMM simulated streamflow is suitable for moderate (7.5 to 35.4 mm/day) to heavy rainfall intensities (35.5 to 124.4 mm/day). The finding of the present work can be useful for TRMM based studies for water resources management over the similar parts of the world

Delineating the drainage structure and sources of groundwater flux for Lake Basaka, Central Rift Valley Region of Ethiopia

Abstract: As opposed to most of the other closed basin type rift valley lakes in Ethiopia, Lake Basaka is found to be expanding at an alarming rate. Different studies indicated that the expansion of the lake is challenging the socio-economics and environment of the region significantly. This study result and previous reports indicated that the lake’s expansion is mostly due to the increased groundwater (GW) flux to the lake. GW flux accounts for about 56% of the total inflow in recent periods (post 2000) and is found to be the dominant factor for the hydrodynamics and existence of the lake. The analysis of the drainage network for the area indicates the existence of a huge recharge area on the western and upstream side of the catchment. This catchment has no surface outlet; hence most of the incoming surface runoff recharges the GW system. The recharge area is the main source of GW flux to the lake. In addition to this, the likely sources/causes of GW flux to the lake could be: (i) an increase of GW recharge following the establishment of irrigation schemes in the region; (ii) subsurface inflow from far away due to rift system influence, and (iii) lake neotectonism. Overall, the lake’s expansion has damaging effect to the region, owing to its poor water quality; hence the identification of the real causes of GW flux and mitigation measures are very important for sustainable lake management. Therefore a comprehensive and detailed investigation of the parameters related to GW flux and the interaction of the lake with the GW system of the area is highly recommended

Linking distributed hydrological processes with ecosystem vegetation dynamics and carbon cycling: Modelling studies in a subarctic catchment of northern Sweden

The Arctic and Subarctic regions are of particular importance to the global climate change and are now experiencing a climate warming that is higher than the global average. Around 50% of the global soil carbon is stored in high latitude soils, especially in permafrost and peatland soils. Permafrost thawing, speeding up the decomposition of previously frozen soil carbon, is expected to result in strongly positive feedbacks to global warming. Meanwhile, increased air temperature may strongly impact vegetation growth and distributions in this region. Dynamic ecosystem models are powerful tools to study climate change influences on ecosystem processes and also to quantify ecosystem feedbacks to the atmosphere. However, these models often focus on the vertical transfer of carbon and water between the atmosphere, the land surface vegetation and soils. Therefore, they generally do not consider the horizontal water and soluble carbon flows between the modelled spatial units (grid cells), which could result in an incomplete estimation of water and carbon budgets, especially for climatically sensitive high latitude regions. In this thesis, we aim to overcome this limitation by implementing spatial topographical indices into a state-of-the-art dynamic ecosystem model, LPJ-GUESS, and to incorporate water and carbon (mainly dissolved organic carbon, DOC) interactions between the grid cells. Modelling approaches and algorithms developed in this thesis were applied to study the subarctic Stordalen catchment, located in northern Sweden, and to explore the potential influence on the model’s hydrological and ecological estimations. Extensive sets of observation data were used for model evaluation throughout. We proposed a distributed hydrological (DH) approach to dynamically simulate water flow from cell to cell within the catchment and compared the hydrological and ecological impacts resulting from different flow routing algorithms. The results indicate an improved accuracy of runoff estimation when using the proposed DH scheme in the Stordalen catchment. They also show that the choice of flow algorithm can have strong impacts on water and carbon flux estimations in this region. Furthermore, a complete estimation of the catchment carbon budget was assessed using our developed model. We found that the catchment is a carbon sink at present and could become a stronger sink in the near future, a result which is, however, very dependent on future atmospheric CO2 concentrations and methane (CH4) emissions from the peatlands. Additionally, the model was further extended to dynamically model soil water DOC and the lateral transport of DOC across the landscape. The modelled outputs suggest that DOC production and mineralization largely contribute to DOC fluxes and that wet fen peatland is and will be a hotspot for DOC export. In conclusion, this thesis demonstrates the feasibility of implementing topographical indices into LPJ-GUESS to describe water flows, and the importance of considering spatial heterogeneity in hydrological conditions when modelling carbon dynamics at high latitudes. Furthermore, the integration of vertical and horizontal carbon fluxes at high spatial resolutions can be used to provide more accurate estimations of a complete carbon budget and can dynamically simulate the fate of different carbon components in response to climate change

Evaluating ephemeral gullies with a process-based topographic index model

Soil conservation practices have been implemented to control soil degradation from sheet and rill erosion, but excessive sediment runoff remains among the most prevalent water quality problems in the world. Ephemeral gully (EG) erosion has been recognized as a major source of sediment in agricultural watersheds; thus, predicting location and length of EGs is important to assess sediment contribution from EG erosion. Geomorphological models are based on topographic information and ignore other important factors such as precipitation, soil, topography, and land use/land management practices, whereas physically based models are complex, require detailed input information, and are difficult to apply to larger areas. In this study, an approach was developed to incorporate a process-based Overland Flow-Turbulent (OFT) EG model that contained factors accounting for drainage area, surface roughness, slope, soil critical shear stress, and surface runoff in the ArcGIS environment. Two hydrologic models, Soil Water Assessment Tool (SWAT) and ArcCN-Runoff (ACR), were adopted to simulate precipitation excess in Goose Creek watershed in central Kansas, USA. These two realizations of the OFT model were compared with the Slope-Area (SA) topographic index model for accuracy of EG location identification and length calculation. The critical threshold index in the SA model was calibrated in a single field in the watershed prior to EG identification whereas the OFT models were uncalibrated. Results demonstrated overall similar performance between calibrated SA model and uncalibrated OFT-SWAT model, and both outperformed the uncalibrated OFT-ACR model. In simulation of EG location, the OFT-SWAT model resulted in 12% fewer false negatives but 8% more false positives than the SA model, compared with 19% fewer false positive and 6% more false negatives than the OFT-ACR model. Greater errors in runoff estimation by ACR translated directly into errors in EG simulation. All models over-predicted EG lengths compared with observed data, though OFT-SWAT and SA models did so with better fit exceedance probability curves, about zero Nash-Sutcliff model efficiency and ≤40% bias compared to -3 model efficiency and >100% bias for OFT-ACR. Success of the uncalibrated OFT-SWAT model in producing satisfactory predictions of EG location and EG length shows promise for process-based EG simulation. The OFT-SWAT model used data and parameters also commonly used for SWAT model development, which should simplify its adoption to other watersheds and regions. Further testing is needed to determine the robustness of the OFT-SWAT model to dissimilar field and hydrologic conditions. It is expected that inclusion of more site-specific physical properties in OFT-SWAT would improve model performance in predicting location and length of EGs, which is essential for accurate estimation of EG sediment erosion rates

Leveraging Crowdsourced Navigation Data In Roadway Pluvial Flash Flood Prediction

This dissertation develops and tests a new data-driven framework for short-term roadway pluvial flash flood (PFF) risk estimation at the scale of road segments using crowdsourced navigation data and a simplified physics-based PFF model. Pluvial flash flooding (PFF) is defined as localized floods caused by an overwhelmed natural or engineered drainage system. This study develops a data curation and computational framework for data collection, preprocessing, and modeling to estimate the risk of PFF at road-segment scales. A hybrid approach is also developed that couples a statistical model and a simplified physics-based simulation model in a machine learning (ML) model to rapidly predict the risk of roadway PFF using Waze alerts in real-time

도시홍수 저감을 위한 근거기반 계획 : 서울시를 중심으로

학위논문 (석사) -- 서울대학교 대학원 : 농업생명과학대학 생태조경·지역시스템공학부(생태조경학), 2021. 2. 강준석.최근 기후변화로 인해 발생되고 있는 사회/경제적 피해는 급속히 증가하고 있다. 기후변화로 인한 2차적 피해로는 폭염, 홍수 등이 있다. 그중에서 극한 강우는 도심지역에 큰 피해를 발생시키고 있다. 대표적으로는 2011년 발생한 집중호우 등이 있는데, 당시에는 최대 110.5 mm/hr의 기록적인 강수가 내렸다. 현대 도시에서 발생하는 홍수의 대부분 원인은 불투수성 포장면의 급격한 증가와 내수배제 불능, 물순환 시설 부재 등의 원인이 있다. 기상청에서 제공하는 기후변화 시나리오에 따르면, 향후 100년간 도시의 평균 강수량은 줄어들 것으로 파악된다. 하지만, 일시에 폭우가 내리는 빈도가 증가하고 국지성 피해가 뚜렷하게 발생할 것으로 판단된다. 현재 상태의 기반시설들에 보수나 방어기술이 수립되지 않으면, 그 피해는 상당할 것으로 판단된다. 이에 본 연구는 총 세 가지 연구 목표를 수립하여 수행하였다. 첫 번째, 기상청에서 제공하는 기후변화 시나리오(RCP 4.5/RCP 8.5)로 인해 발생할 수 있는 향후 80년(2020년-2100년)의 도시 홍수 피해량을 정량적으로 분석한다. 두 번째, 정량적으로 분석된 피해량에 기반한 재해 저감 시설을 선정하고, 재해의 저감량을 분석한다. 이를 통해 근거 기반(Evidence-Based Planning)의 시설배치 및 설계한다. 재해 저감 시설은 미래 세대가 지속적으로 사용할 수 있는 친환경(Eco-Friendly) 시설물을 선정하였다. 세 번째, HCFD (Hazard Capacity Factor Design) 모델의 개발을 통해, 향후 변화할 수 있는 시설물들의 용량과 성능에 대해 정량적으로 분석한다. HCFD 모델은 저감 기술을 유지하는 방법을 고려하는데 사용된다. 이러한 목표를 달성하기 위해서 방어 기술로 총 세 가지를 도입하였다. 저류조, 투수성 포장 그리고 생태수로가 이에 해당한다. 저류조의 경우, 환경부에서 지정하고 있는 법령을 참고하여 도입 가능한 용량을 파악하였다. 투수성포장과 생태수로는 법령으로 명확히 규정하는 설계 지침이 없기에, 타 연구 보고서를 참고하였다. 각 기술들의 도입 규모를 산정하기 위해서 Arc-GIS ArcHydro Plug in을 사용하였고 Watershed를 분석하였다. Watershed에 영향을 미치는 범위를 파악하기 위해서 기후변화시나리오에서 제공하는 강수량을 시간 단위로 분석하였고, 이를 위해 Huff Curve 공식을 사용하였다. 위에서 언급된 세 가지 기술은 빗물의 저장 용량을 증가시켜 홍수 완화에 기여할 것으로 판단된다. 세 가지 기술을 모두 도입하였을 때 2050년과 2060년에는 RCP 8.5 시나리오의 모든 홍수피해를 저감할 수 있을 것으로 판단된다. 2070년 이후에는 유출이 발생할 것으로 분석되지만, 적응 기술을 통해 홍수를 크게 줄일 수 있을 것으로 예측된다. 본 연구 논문에서는 10년 단위의 홍수와 적응량을 산정하였지만, 추후 후속 연구에서는 1년 단위의 분석이 실시되어야 할 것으로 판단된다. 또한 저류조 내부에 퇴적되는 비점오염원의 청소 시기가 산정되었습니다. 저류조의 경우 MOUSE 회귀 분석을 통해 내부에 축적된 비점오염원 제거 시기를 산정하였다. 빗물 저류조 내부 관리는 크게 주의단계, 일반단계, 안전단계로 지방자치단체를 구분하였다. 주의단계에 해당하는 지방자치단체는 9개, 일반단계에 해당하는 지방자치단체는 10개, 안전단계에 해당하는 지방자치단계는 5개가 해당한다. 이 연구의 결과를 통해 도출된 결론 및 의의는 세 가지로 요약된다. 첫째, 본 연구는 기후변화 시나리오에 따라 발생할 수있는 홍수 가능성을 10년 주기로 분석했다.RCP 8.5 시나리오와 RCP 4.5 시나리오 모두 2070년 이후에 빈번한 홍수의 추이를 볼 수 있었다. RCP 8.5 시나리오의 2090년에 강수량이 가장 많을 것으로 예상된다. RCP 4.5 시나리오 2100년의 경우, 최대 690 mm, 시간당 강수량은 238 mm까지 내릴 것으로 판단된다. 두 번째, 본 연구 논문은 각 기술의 용량을 자치구별로 분석하였다. 본 연구에서 가정한 설치 규정에 따르면 서울시 전역에 설치할 수 있는 빗물 저류조의 부피는 776,588 m³, 투수성 포장은 89,049 m³, 생태수로는 81,986 m³이다. 각 지방자치단체가 두 가지 기술만을 적용하였을 때 효율적인 조합을 제안한 것은 본 연구가 가지는 중요한 의의입니다. 셋째, 각 재해저감 기술로 저감할 수 있는 유출량을 정량화했습니다. 이 연구는 지역 차원의 분산적 형태의 홍수가 더 자주 발생하고, 재난 저감 기술의 정량적 효과를 분석하였다는데 의의가 있다. 본 연구의 한계는 네 부분으로 나눌 수 있다. 첫 번째 한계는 기후변화 시나리오에 대한 불확실성이다. 탄소 배출량이나 시나리오의 변화는 강수량 값을 크게 변경할 수 있기 때문에 오류가 적은 시나리오를 사용하면 향후 연구가 더 중요한 연구로 발전할 것으로 판단된다. 최근 기후변화 시나리오의 불확실성을 줄일 수 있는 연구가 활발히 진행 중이기 때문에, 첫 번째 한계점을 보완한 후속연구가 진행될 것이라 판단된다. 두 번째 한계는 RCP 4.5 / RCP 8.5 시나리오가 10년의 빈도로 수행되었다는 것이다. 세 번째 한계점은 사회 변화 요인이 반영되지 않았다는 것 입니다. 네 번째는 검증의 한계입니다. 본 연구에서는 서울시의 유출수를 계산하기 위해 산술 방정식과 GIS Arc-hydro를 사용하였다.추후 SWMM 등의 홍수 해석 프로그램을 활용하여 추가적인 검증이 되어야 한다. 따라서, 위의 네 가지 한계를 극복하기 위해 후속 연구가 수행되어야 할 것으로 판단된다. 특히 첫 번째 문제점인 기후변화 시나리오의 불확실성 한계점은 후속되는 세 가지 한계점을 발생시키기에, 필수적으로 해결되어야 한다.The social and economic damage caused by climate change has increased rapidly over the last several decades, with increasing instances of heat waves, floods, and extreme rainfall. Of these, the damage caused by extreme rainfall is still ongoing, and more extreme rainfall is expected in Korean Peninsula in the future. There was up to 110.5 mm/hr of rainfall in Seoul, which caused 69 casualties and approximately USD 27.6 million in economic damage. Most of the causes of flooding in modern cities include a sharp increase in non-permeable packaging surfaces and a lack of water circulation facilities. According to climate change scenarios provided by the Korea Meteorological Administration, the average rainfall in cities over the next 100 years is expected to decrease. However, it is predicted that future instances of heavy rain will occur in the future, causing large amounts of local damage. If the current state of infrastructure is not equipped with repair or mitigating technologies, the damage will be significant. This study was conducted based on the following three objectives. First, to quantitatively analyze urban flood damage over the next 80 years (2020-2100) that could be caused by the climate change scenario provided by the Korea Meteorological Administration. Second, this study was selected disaster mitigation facilities and analyzed their impact on disaster mitigation. It also arranges and designs facilities based on an evidence-based planning. Sustainable facilities were selected by introducing eco-friendly facilities for future generations as mitigate technologies. Third, through the development of the HCFD (Hazard Capacity Factor Design) model, the capacity and performance of the facilities that may change in the future were analyzed. HCFD model was used to consider ways to maintain mitigating technologies. In order to achieve these goals, a total of three mitigating technologies have been installed. This includes water tanks, permeable pavement, and ecological waterways. In the case of water tanks, the capacity was calculated by referring to the statutes designated by the Ministry of Environment. Also, an Arc-GIS ArcHydro Plug-in was used to calculate the scale of each technology and watershed was analyzed. The precipitation provided by the climate change scenario was analyzed on an hourly basis to determine the extent to which watershed affects it, and the Huff dimensionless curve was used for this purpose. These three mitigating technologies can contribute to flooding by increasing the storage capacity of rainwater. This study suggests that all floods can be reduced by RCP8.5 in 2050, 2060. Although there will be run-off after 2070, it is analyzed that technology will significantly reduce the volume of the flood. It is deemed that a one-year analysis should be conducted in consideration of the maintenance aspects in the future. Furthermore, removal timing of the non-point source pollutant was calculated. In the case of water tanks, the amount of non-point source pollutant accumulated inside and the removal timing were calculated through MOUSE regression analysis. Internal management of water tank is classified into caution stage, general stage and safe stage. There were nine local governments that corresponded to the caution stage, ten local governments of general stage and five local governments of safe stage. There are three main conclusions drawn from the results of this study. First is that the possibility of flooding that could occur according to climate change scenarios was analyzed at a 10-year frequency. Both the RCP 8.5 scenario and RCP 4.5 scenario showed frequent flooding after 2070. For the RCP 8.5 scenario, it is predicted that the year 2090 has the highest amount of precipitation. However, for RCP 4.5 scenario 2100, the maximum daily rainfall is approximately 690 mm, with hourly precipitation of 238 mm. The second is that capacity of each technology was analyzed. According to the installation rules assumed in this study, the volume of water tanks that can be installed throughout the Seoul Metropolitan Government is 776,588 m³, permeable pavement is 89,049 m³, ecological waterway is 81,986 m³. It is siginificant that each local government has suggested an efficient combination of two technologies. Third, the amount of runoff that can be reduced by each mitigating technology was quantified. This study has identified that flooding at the local level will be more frequent and is meaningful in analyzing the quantitative effects of disaster mitigation technologies. Besides, when each local government installed flood mitigation technology in the future, quantification data would be provided to ensure optimized decision making for each situation. The limitations of this study can be diagnosed by dividing them into four parts. The first limitation is uncertainty about climate change scenarios. Since changes in carbon emissions or scenarios can significantly change precipitation values, it is believed that future studies will develop into a more significant study if a scenario with fewer errors is used. The second limitation is that the study was conducted at a frequency of 10 years, as both RCP4.5 / RCP8.5 scenarios were analyzed daily. Third, social change factors are not reflected. Fourth is the limitation of verification. In this study, an arithmetic equation and GIS Arc-hydro were used to calculate the run-off in the Seoul Metropolitan Government. The most ideal method to verification is to compare the results with other software. The reliability of this study can be improved by comparing the amount of runoff before applying technologies using programs such as SWMM, STORM, and MUSIC. Future studies, therefore, should be carried out to overcome the above four limitations. In particular, uncertainty problem of the climate change scenario should be solved.Chapter 1. Introduction 1 1.1 Background 1 1.2 Objectives 5 1.3 Scope 6 1.4 Definition of Floods 8 1.5 Vulnerability 11 Chapter 2. Literature Review 14 2.1 Overview 14 2.2 Policy Review 19 2.3 Types of Defense Technologies 21 2.4 Types of Analysis Programs 33 2.5 Target Site 37 2.6 Climate Change Scenarios 38 Chapter 3. Methodology 41 3.1 Hydrologic Analysis 41 3.2 Application of Mitigation Technology and Estimation of flood damage 46 3.3 Calculation of Current Rainfall Capacity and Run-off 48 3.4 Estimation of Hourly Precipitation in Climate Change Scenarios (RCP 8.5/RCP 4.5) using the Huff curve 51 3.5 The Concept of HCFD (Hazard Capacity Factor Design) Model for observing Future Ability Changes of Facilities 53 Chapter 4. Results 56 4.1 Site Analysis 56 4.2 The 10-year frequency flood damage analysis 65 4.3 Variation of the flooded area after application of disaster mitigating technology 71 4.4 Amount of non-point pollutant deposits in the water tank and maintenance time using the MOUSE regression equation 86 Chapter 5. Summary and Conclusions 94Maste

Geo-Spatial Analysis in Hydrology

Geo-spatial analysis has become an essential component of hydrological studies to process and examine geo-spatial data such as hydrological variables (e.g., precipitation and discharge) and basin characteristics (e.g., DEM and land use land cover). The advancement of the data acquisition technique helps accumulate geo-spatial data with more extensive spatial coverage than traditional in-situ observations. The development of geo-spatial analytic methods is beneficial for the processing and analysis of multi-source data in a more efficient and reliable way for a variety of research and practical issues in hydrology. This book is a collection of the articles of a published Special Issue Geo-Spatial Analysis in Hydrology in the journal ISPRS International Journal of Geo-Information. The topics of the articles range from the improvement of geo-spatial analytic methods to the applications of geo-spatial analysis in emerging hydrological issues. The results of these articles show that traditional hydrological/hydraulic models coupled with geo-spatial techniques are a way to make streamflow simulations more efficient and reliable for flood-related decision making. Geo-spatial analysis based on more advanced methods and data is a reliable resolution to obtain high-resolution information for hydrological studies at fine spatial scale

Modelling in ungauged catchments using PyTOPKAPI : a case study of Mhlanga catchment.

Masters Degree. University of KwaZulu-Natal, Durban.Hydrological modeling of rainfall-runoff processes is a powerful tool used in various water resources applications, including the simulation of water yield from ungauged catchments. Many rivers in developing countries are poorly gauged or fully ungauged. This gives rise to a challenge in the calibration and validation of hydrological models. This study investigated the applicability of PyTOPKAPI, a physically based distributed hydrological model, in simulating runoff in ungauged catchments, using the Mhlanga River as a case study. This study is the first application of the PyTOPKAPI model to simulate daily runoff on an ungauged catchment in South Africa. The PyTOPKAPI model was parameterised using globally available digital elevation data (DEM), satellite-derived land cover, soil type data and processed hydro-meteorological data collected from various sources. Historical 30-year (1980-2009) quaternary monthly streamflow (from a well-tested and calibrated model) and daily meteorological variables (rainfall, temperature, humidity and so on) were obtained. The rainfall data were subjected to double mass curve test to check for consistency. The monthly streamflow was transposed to the catchment and disaggregated to daily streamflow time step. The PyTOPKAPI model was calibrated using an average runoff ratio as an alternative to matching streamflow data that is usually used for model calibrations. The simulated results were thereafter compared with the disaggregated monthly quaternary data. The model results show good overall performance when compared with the average runoff ratio, monthly disaggregated streamflow and the expected mean annual runoff in the catchment. In general, PyTOPKAPI can be used to predict runoff response in ungauged catchments, and thus may be adopted for water resources management applications