Estimation of Probable Maximum Precipitation (PMP) and Probable Maximum Flood (PMF) Using GSSHA Model (Case Study Area Upper Citarum Watershed)

Probable Maximum Flood (PMF) used in the design of hydrological structures reliabilities and safety which its value is obtained from the Probable Maximum Precipitation (PMP). The objectives of this study are to estimate PMP and PMF value in Upper Citarum Watershed and understand the impact from different PMP value to PMF value with two scenarios those are Scenario A and B. Scenario A will calculate the PMP value from each Global Satellite Mapping of Precipitation (GSMaP) rainfall data grid and Scenario B calculate the PMP value from the mean area rainfall. PMP value will be obtained by the statistical Hershfield method, and the PMF will be obtained by employed the PMP value as the input data in Gridded Surface Subsurface Hydrologic Analysis (GSSHA) hydrologic model. Model simulation results for PMF hydrographs from both scenarios show that spatial distribution of rainfall in the Upper Citarum watershed will affect the calculated discharge and whether Scenario A or B can be applied in the study area for PMP duration equal or higher than 72 hours. PMF peak discharge for Scenario A is averagely 13,12% larger than Scenario B.

Post Wildfire Debris Flow and Flood Analysis of the September 2020 Badger Fire in the Trapper Creek and Rock Creek Watersheds, Idaho, USA.

<p>There are several different infiltration, overland flow routing, and channel routing schemes that can be used in conjunction with recommended hydrodynamic and infiltration parameter values, which are found within the literature, to provide critical flooding assessments for stakeholders and decision makers.  We focus on post wildfire debris flow and flood analysis in two tributaries of the Snake River in Idaho, Trapper Creek and Rock Creek.  The Badger Fire started on September 12, 2020 in the Sawtooth National Forest in Idaho, USA, and burned sub-alpine fir, lodgepole pine, juniper, mountain brush and grass communities, in the upper part of both the Trapper Creek and Rock Creek watersheds.  Trapper Creek has a U.S. Geological Gaging station, and there are two snow gaging sites available.   The biggest concern for flooding and debris flow is the result of a wintertime rain-on-snow event, which resulted in the largest storm in the gaging record period.    </p><p>To estimate runoff in ungaged stream locations, existing process-based hydrodynamic models can be applied in a distributed form to solve the governing equations for mass, momentum and energy in a spatially explicit way. The purpose of this study is to predict potentially inundated land areas as a result of a rain-on-snow event, using the data in the gages basin to provide flood analysis information for both the gaged (Trapper Creek) and ungaged watershed (Rock Creek).  Rain-on-snow events are rainfall events that occur on the snowpack and frozen ground, resulting in a larger magnitude and volume of streamflow.  To predict these flows, Gridded Surface Subsurface Hydrologic Analysis (GSSHA) watershed models are prepared and calibrated to simulate rain-on-snow events in both watersheds.  The runoff generated from a two dimensional overland flow grid is transferred over land with a finite volume numerical method into a one dimensional channel network.  The channel network also uses a finite volume method.    The consistency in the identified range of the parametric values and their physical applicability make GSSHA an ideal candidate for this study, as the model equations provide a methods to evaluate a rain-on-snow event.</p>

Topographic and Hydrologic Analyses using Geographic Information System (GIS): A Case Study of Karbala City-Iraq

Analyses are the power point of GIS because GIS can process and analyze different data such as spatial and attribute data, leading to obtaining new results for supporting decision-makers. This research aims to study two types of advanced analyses include; topographic and hydrologic analyses for the western part of Karbala in Iraq using GIS. The topographic analysis aims to know surface terrain and obtain the results of digital maps that show the simulation of the study area based on some methods and tools in GIS after creating DEM for study area from field survey methods such as slope, aspect, hill shades, and contour maps. After that, hydrologic analysis is done based on DEM of the study area, where this analysis gives digital maps that show the main and minor hydrological properties of the region, such as flow direction, flow accumulation, stream order, and basin maps. These analyses are very important for making decisions in studying the topographic and hydrologic properties of any region in Iraq, and the GIS technique offers a save in time, cost and efforts.

Case Study: Reconstructing the 2015 Dulcepamba River Flood Disaster

ABSTRACT In March 2015, the village of San Pablo de Amalí on the Dulcepamba River in Ecuador was hit by a flood that killed three residents, destroyed five homes, and eroded several hectares of farmland. Residents asserted that the recent construction of a run-of-the-river hydroelectric facility built in the river channel directed flood flows toward the village, causing the associated damage and fatalities. We conducted a forensic hydrologic and hydraulic analysis of the catchment to assess potential causal mechanisms affecting flooding, including the construction of the hydroelectric facility. Hydrologic analysis demonstrated that the river flows produced by the March 2015 storm were equivalent to a 6-year return interval event, with a discharge of 58.6 cms, not the much more extreme 33-year return interval, 400-cms event that had been suggested in a report produced by the hydroelectric company. Hydraulic modeling determined an ∼2-m elevation surcharge of water attributable to the hydroelectric facility, suggesting that damage to the village would not have occurred without the obstruction created by debris blockage of the hydroelectric plant intake. Hydrologic modeling also quantified monthly totals of water availability in the Dulcepamba watershed, including average dry-season flow volumes. When compared to flow volumes allocated to the hydroelectric operator, the modeling indicated that the seasonal water availability in the Dulcepamba watershed is not sufficient to collectively meet the minimum in-stream environmental flow requirements, the agriculture demands from local subsistence irrigators, and the flow volumes allocated to the hydroelectric operator.

Being Bayesian: Discussions from the Perspectives of Stakeholders and Hydrologists

Bayes’ Theorem is gaining acceptance in hydrology, but it is still far from standard practice to cast hydrologic analyses in a Bayesian context—especially in the realm of hydrologic practice. Three short discussions are presented to encourage more complete adoption of a Bayesian approach. The first, aimed at a stakeholder audience, seeks to explain that an informal Bayesian analysis is the default approach that we all take to any decision made under uncertainty. The second, aimed at a general hydrologist audience, seeks to establish multi-model approaches as the natural choice for Bayesian hydrologic analysis. The goal of this discussion is to provide a bridge from the stakeholder’s natural approach to a more formal, quantitative Bayesian analysis. The third discussion is targeted to a more advanced hydrologist audience, suggesting that some elements of hydrologic practice do not yet reflect a Bayesian philosophy. In particular, an example is given that puts Bayes Theory to work to identify optimal observation sets before data are collected.

Combining Hydrologic Analysis and Life Cycle Assessment Approaches to Evaluate Sustainability of Water Infrastructure: Uncertainty Analysis

The goal of this research is identifying major sources of uncertainty of an environmentally-sustainable urban drainage infrastructure design, based on hydrologic analysis and life cycle assessment (LCA). The uncertainty analysis intends to characterize and compare relative roles of unreliability, incompleteness, technological difference, and spatial and temporal variation in life cycle impact assessment (LCIA) data, as well as natural variability in hydrologic data. Uncertainties are analyzed using a robust Monte Carlo simulation approach, performed by High Throughput Computing (HTC) and interpreted by Morse-Scale regression models. The uncertainty analysis platform is applied to a watershed-scale LCA of rainwater harvesting systems (RWH) to control combined sewer overflows (CSOs). To consider the watershed-scale implications, RWH is simulated to serve for both the water supply and CSO control in an urban watershed in Toledo, Ohio, USA. Results suggest that, among the studied parameters, rainfall depth (as a hydrologic parameter) caused more than 86% of the uncertainty, while only 7% of the uncertainty was caused by LCIA parameters. Such an emphasis on the necessity of robust hydrologic data and associated analyses increase the reliability of LCA-based urban water infrastructure design. In addition, results suggest that such a topology-inspired model is capable of rendering an optimal RWH system capacity as a function of annual rainfall depth. Specifically, if the system could capture 1/40th of annual rainfall depth in each event from rooftops, the RWH system would be optimal and, thus, lead to minimized life cycle impacts in terms of global warming potential (GWP) and aquatic eco-toxicity (ETW). This capture depth would be around 2.1 cm for Toledo (given an 85 cm/year rainfall and 200 m2 typical roof area), which could be achieved through an RWH system with 4.25 m3 capacity per household, assuming a uniform plan for the entire studied watershed. Capacities smaller than this suggested optimal value would likely result in loss of RWH potable water treatment savings and CSO control benefits, while capacities larger than the optimal would likely incur an excessive wastewater treatment burden and construction phase impacts of RWH systems.

Water Conservation at Chandigarh University, Gharuan, Punjab-Recommendations and Observations

The technical aspect of this paper is water conservation. Water table is getting depleted in the area because of rapid withdrawal of water. University needs nearly twenty lakhs liters of water every day. Farmers in the adjoining areas also pump out lot of water required for irrigating paddy. Paddy needs 150 cm of water for growth stage .Part of it is met by monsoon and largely by pumping out of water. There had been a decline of 50-100 cm per year sin the water table in the last two decades. All this has led to the need for water conservation. It involves harvesting, recycling of water and improving infiltration. The campus works on the principle of zero discharge. It means we are not discharging water into any municipal drain or rivulet. Waste water is recycled through 1.5mlpd sewage treatment plant and used for horticulture. Roof top rainwater and storm water is harvested through ten rain water harvester located after proper hydrologic analysis. Interlocking tiles are preferred over impermeable pavement to improve infiltration