Andrzej Wałęga

Application of HEC-HMS programme for the reconstruction of a flood event in an uncontrolled basin / Zastosowanie programu HEC-HMS do odtworzenia wezbrania powodziowego w zlewni niekontrolowanej

Abstract The paper presents an assessment of the applicability of HEC-HMS programme to simulate a precipitation flood event in an ungauged basin. The programme has been developed by the Department of the Army Corps of Engineers and enables conducting hydrological calculations for basins with different characteristics and including a number of meteorological factors. The application of this model in Polish conditions was verified in the basin of the Stobnica River - a right tributary of the Wisłok River. The calculations were carried out for the flood event caused by a continuous rain, which occurred in April 1998. Four hydrological models were compared: geomorpho-climatic instantaneous unit hydrograph by Nash - GcIUH_Nash, Snyders synthetic unit hydrograph with the determination of parameters by regression models - Snyder_reg and standard method - Snyder_ stand and Clarks instantaneous unit hydrograph - IUH_Clark, where the model parameters were optimized in the programme. The calculations revealed that the best simulation results were obtained with the Snyder_stand and Snyder_reg models. Further research should be directed to verifying the applicability of HEC- -HMS programme for hydrological analyses of much more extensive hydrometric material and basins with different characteristics. Streszczenie W pracy dokonano oceny możliwości stosowania programu HEC-HMS do symulacji wezbrania opadowego w zlewni niekontrolowanej. Program ten został opracowany przez Korpus Inżynierów Armii Amerykańskiej i umożliwia prowadzenie obliczeń hydrologicznych dla zlewni o różnej charakterystyce i z uwzględnieniem różnych czynników meteorologicznych. Zastosowanie tego modelu w warunkach polskich zostało zweryfikowane w zlewni Stobnicy - prawostronnego dopływu Wisłoka. Obliczenia przeprowadzono dla wezbrania wywołanego deszczem rozlewnym, które wystąpiło w kwietniu 1998 r. Porównano cztery modele hydrologiczne: geomorfoklimatyczny hydrogram jednostkowy Nasha - GcIUH_Nash, syntetyczny hydrogram jednostkowy Snydera z określeniem parametrów wzorami regresyjnymi - Snyder_reg i metodą standardową - Snyder_stand oraz z wykorzystaniem chwilowego hydrogramu jednostkowego Clarka - IUH_Clark, gdzie parametry modelu były optymalizowane w programie. Obliczenia wykazały, że najlepsze rezultaty symulacji uzyskano, stosując model Snyder_stand i Snyder_reg. Dalsze badania powinny iść w kierunku weryfikacji możliwości stosowania programu HEC-HMS do analiz hydrologicznych na znacznie bardziej obszernym materiale hydrometrycznym i w zlewniach o różnej charakterystyce.

The use of NRCS synthetic unit hydrograph and Wackermann conceptual model in the simulation of a flood wave in an uncontrolled catchment

Abstract The paper presents the results of using two models: a conceptual model of Wackermann and a NRCS-UH synthetic unit hydrograph, for flow calculation in uncontrolled catchment of the Słonka, Poland. These models were chosen because of simplicity of models’ parameters evaluation, what is important from engineering calculation point of view. Flows with the probability of exceed amounting to 0.5%, 1%, 2%, 5%, 10%, 20%, and 50% and for different levels of the catchment moisture were evaluated. The flood waves generated in the Wackermann model were characterized by a short duration (over 2 hours), shorter concentration time (about 1 hour), and by about 70% higher peak flow values than those generated using the NRCS-UH method. A common feature of both methods were higher values of peak flows for the third level of the catchment moisture, as compared to the second level. It is also worth noticing that in both methods no flood wave was generated for the probabilities of 10, 20 and 50% and for the second level of the catchment moisture. It was assumed that hydrographs made with use Wackermann model better describe flood wave in mountain river, which Słonka is. W pracy przedstawiono wyniki analiz z wykorzystaniem dwóch modeli - konceptualnego modelu Wackermana oraz syntetycznego hydrogramu jednostkowego NRCS-UH - do określenia przepływów w zlewni rzeki Słonka, znajdującej się na obszarze Polski. Wybrane modele charakteryzują się łatwością określenia danych wejściowych do modelu, co jest istotne w aspekcie obliczeń inżynierskich. Obliczenia wykonano dla przepływów o prawdopodobieństwie wystąpienia przekroczenia wynoszącym: 0,5%, 1%, 2%, 5%, 10%, 20% i 50 dla różnych poziomów uwilgotnienia zlewni. Fale wezbraniowe, wygenerowane za pomocą modelu Wackermana, charakteryzowały się krótkim czasem trwania - ponad 2 godziny, krótszym czasem koncentracji - ok. 1 godziny i o ok. 70% większymi wartościami przepływów maksymalnych niż w przypadku fal wygenerowanych z wykorzystaniem metody SCS. Cechą wspólną obu metod były większe wartości przepływów maksymalnych dla III poziomu uwilgotnienia w stosunku do poziomu II. Można również zauważyć, że w przypadku obu metod oraz II poziomu uwilgotnienia zlewni nie wygenerowano fali wezbraniowej o prawdopodobieństwach przewyższenia 10, 20 i 50%.

The evaluation of heavy metal content in water and sediments of small reservoirs in light of various environmental quality regulations

This article reports the heavy metal concentrations assessed both in bottom sediments and water flowing into two small reservoirs at Krempna and Zesławice, southern Poland. The experiments were carried out in spring, summer, autumn and winter 2010–2011. The resulting concentrations of lead, cadmium, nickel, chromium and copper were compared with the Environmental Quality Standards, guidelines of the Regulation of the Minister of Environmental Protection, regulations of the Polish Geological Institute and State Institute of Environment Protection, Institute of Soil Science and Plant Cultivation, and with the regulations adopted in Germany, Denmark, the United States and Canada. Regarding the total heavy metal concentrations, water flowing into the examined reservoirs was not polluted. The highest concentrations of heavy metals were found in water flowing into the reservoirs in spring and summer. The heavy metal concentrations in sediments of the reservoirs at Krempna and Zesławice were much higher than the concentrations of the elements discussed present in waters flowing into these reservoirs.

Direct runoff assessment using modified SME method in catchments in the Upper Vistula River Basin

Correct determination of direct runoff is crucial for proper and safe dimensioning of hydroengineering structures. It is commonly assessed using SCS-CN method developed in the United States. However, due to deficiencies of this method, many improvements and modifications have been proposed. In this paper, a modified Sahu–Mishra–Eldo (SME) method was introduced and tested for three catchments located in the upper Vistula basin. Modification of SME method involved a determination of maximum potential retention S based on CN parameter derived from SCS-CN method. The modified SME method yielded direct runoff values very similar to those observed in the investigated catchments. Moreover, it generated significantly smaller errors in the direct runoff estimation as compared with SCS-CN and SME methods in the analyzed catchments. This approach may be used for estimating the runoff in uncontrolled catchments.

Comparison of SCS-CN Determination Methodologies in a Heterogeneous Catchment

The aim of this study was to assess the runoff amount from a catchment characterized by diverse land uses by using the Soil Conservation Service Curve Number (SCS-CN) method based on Curve Number (CN) defined for dominant homogeneous elementary sub-regions. The calculations employed the SCS-CN method, involving the division of the catchment in two homogeneous parts and determining the runoff amount. The obtained results were compared with the results provided by three other CN determination methods, i.e. the Hawkins function, the kinetics equation, and a complementary error function peak. The catchment is located in a mountain dominated by forest land cover. Empirical CN-Precipitation (CNemp-P) data pairs were analyzed using the mentioned methods, and the highest quality score was achieved from model 1. The results suggest that dividing a catchment into two homogeneous areas and determining their separate CN parameters, used later on to calculate the runoff by means of the presented approach, could be an alternative to the standard methods. The described method is relatively easy, and as it does not require an adoption of numerous parameters, and it can be employed for designing hydraulic facilities.

Usefulness of the Modified NRCS-CN Method for the Assessment of Direct Runoff in a Mountain Catchment

The aim of this study was to evaluate the usefulness of modified methods, developed on the basis of NRCS-CN method, in determining the size of an effective rainfall (direct runoff). The analyses were performed for the mountain catchment of the Kamienica river, right-hand tributary of the Dunajec. The amount of direct runoff was calculated using the following methods: (1) Original NRCS-CN model, (2) Mishra—Singh model (MS model), (3) Sahu Mishra Eldho model (SME model), (4) Sahu 1-p model, (5) Sahu 3-p model, and (6) Q_base model. The study results indicated that the amount of direct runoff, determined on the basis of the original NRCS-CN method, may differ significantly from the actually observed values. The best results were achieved when the direct runoff was determined using the SME and Sahu 3-p model.

Runoff formation in terms of changes in land use - Mściwojów water reservoir area

Abstract Along the paper the size of peak runoff was assessed affected by the influence of changes in water catchment area by land use due to future planned agricultural changes. The investigations were conducted in the Winna Góra catchment area located in Mściwojów, Lower Silesian voivodship at the Mściwojów water reservoir. At present, the catchment is used as arable land, forest and meadows. In the future the area of sealed surfaces such as: roofs, roads and car parks will increase. This can contribute in the change of water balance components. Analyses has shown, that changes in the use of a catchment area lead to reduction of surface flow time from the catchment (less resistance to motion) - in effect it causes increase of the runoff volume at about 28%. The increase of the water runoff volume may have significant influence on the Winna Góra development and functions as well as volume of water run into the Mściwojów water reservoir. To counteract the results of adverse changes caused by the catchment sealing - it is recommended for the investigated area to apply a balanced approach. This would consist of retaining precipitation water in its place of origin. W artykule przedstawiono wielkość zmian odpływu powierzchniowego w wyniku przyszłych planowanych zmian użytkowania rolniczego zlewni. Badania prowadzono w obszarze Winnej Góry znajdującej się w miejscowości Mściwojów (województwo dolnośląskie) w zlewni zbiornika wodnego Mściwojów. Obecnie zlewnia to głównie przestrzeń rolnicza i lasy. W przyszłości obszar powierzchni zlewni dopełnią powierzchnie takie, jak: budynki, drogi i parkingi. Może to przyczynić się do zmiany elementów bilansu wodnego zlewni. Analizy wykazały, że zmiany w użytkowaniu zlewni prowadzą do skrócenia czasu spływów powierzchniowych ze zlewni (mniejsze opory ruchu), co powoduje zwiększenie objętości odpływu o około 28%. Zwiększenie ilości odpływającej wody może mieć znaczący wpływ na rozwój i funkcje Winnej Góry, a także dopływ wody i pojemność zbiornika wodnego Mściwojów.

Influence of changes in land use on the values of maximal peak flows on example of Winna Góra in the neighbourhood of Mściwojów reservoir

In the paper the evaluation of influence of changes in water catchment area land use on the size of peak outflow was conducted. The investigations were conducted in Winna Gora catchment area located in Mściwojow, Lower Silesian voivodeship. The catchment area is 11.78 hectares. At present, the catchment is used as arable land, forest and meadows. In the future the area of sealed surfaces such as: roofs, roads and car parks will increase. This can contribute to the change of water balance components. Analyses has shown, that changes in the use of a catchment area lead to reduction of surface flow time from the catchment (less resistance to motion) – in effect it causes increase of the outflow volume at about 28%. The increase of the water outflow volume may have significant influence on the Winna Gora development. To counteract the results of adverse changes caused by the catchment sealing – it is recommended for the investigated area to apply a balanced approach. This would consist of retaining precipitation water in its place of origin.

The importance of calibration parameters on the accuracy of the floods description in the Snyder’s model

Abstract Comparison of quality of Snyder’s model for determination flood waves was examination in this work. Model parameters were calibrated based on objective functions: percentage error in peak flow (PEPF), percentage error in volume (PEV), peak-weighted root mean square error (PWRMSE), sum of absolute residuals (SAR) and sum of squared residuals (SSR). Quality of model was calculating by Nash-Sutcliffe efficiency coefficient E. Additionally sensitivity of a model was characterized by its flexibility. The analyses were performed in the watershed of Grabinka. It has been found that the use PWRMSE as the objective function allows to obtain the best quality results of simulation. Furthermore, Snyder’s model is flexible to the change of Cp coefficient.

COMPARISON OF METHODS FOR DETERMINING ENVIRONMENTAL FLOW IN SELECTED MOUNTAIN BASINS

The paper describes the way of determining environmental flows, based on the use of Tennant and Tessman methods, a method based on flow duration curves, as well as instream flows using the methods of Kostrzewa. Calculations were conducted for the catchment of Młyniska River (cross-section Zakopane), which is located in upper Dunajec basin. Input data, obtained from the Institute of Meteorology and Water Management, National Research Institute in Warsawincluded observation series of daily flows for the years 2000–2014. The data were evaluated in terms of homogeneity and independence, using the Mann-Kendall-Sneyers. The calculations have shown differences between values of instream flow and environmental flow and also allowed us to conclude that the computed environmental flows were above the level determined by the absolutely low flow. Also conducted that disposable resources of water by Młyniska river, limited by instream flow and environmental flowdo not differ significantly.