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Digital Elevation Model resolution and its impact on the spatial pattern of rainfalltemperature prediction at the catchment scale: The case of the Mille catchment, Ethiopia

Bati Hirpo Gudeta

Meteorology Hydrology and Water Management. Research and Operational Applications

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2022

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Vol. 10, Iss. 1

26--46

EN

In a mountainous catchment, understanding the interaction between DEM resolution and climatic variables is essential for the accurate spatial interpolation of areal mean monthly and annual rainfall and temperature, which is required as an input for further applications such as hydrological and hydraulic modeling, agriculture, and environmental conservation. This case study applied the geostatistical interpolation technique, kriging with external drift (KED), with a digital elevation model (DEM) with various horizontal resolutions, which were used to assess the effects of the DEM horizontal resolutions on the spatial distributions of rainfall and temperature by focusing on interpolating the mean monthly and annual rainfall and temperature over a spatially diversified catchment. The assessment was undertaken using spatially and temporally complete sampled historical climatic datasets, and consequently, the spatial pattern of monthly and annual rainfall (temperature) from east to the west gradually increases or decreases following the DEM elevation increment along the same direction. As a result, the finer-resolution DEM (90-m SRTM-DEM) had a considerable impact on predicting the mean monthly minimum and maximum temperatures, whereas the resampled 500-m SRTM-DEM performed relatively better in mean monthly and annual rainfall and annual minimum temperature estimation values.

2

Improving ANN based streamfow estimation models for the Upper Indus Basin using satellite derived snow cover area

Hassan Muhammad, Hassan Ishtiaq

Acta Geophysica

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2020

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Vol. 68, no. 6

1791--1801

EN

The mountainous catchments often witness contrasting regimes and the limited available meteorological network creates uncertainty in both the hydrological data and developed models. To overcome this problem, remotely sensed data could be used in addition to on-ground observations for hydrological forecasting. The fusion of these two types of data gives a better picture and helps to generate adequate hydrological forecasting models. The study aims at the improvement of ANN-based streamfow estimation models by using an integrated data-set containing, the satellite-derived snow cover area (SCA) with on-ground fow observations. For this purpose, SCA of three sub catchments of Upper Indus Basin, namely Gilgit, Astore and Bunji coupled with their respective gauge discharges is used as model inputs. The weekly stream-fow models are developed for infows at Besham Qila located just upstream of Tarbela dam. The data-set for modeling is prepared through normal izing all variables by scaling between 0 and 1. A mathematical tool, Gamma test is applied to fuse the inputs, and a best input combination is selected on the basis of minimum gamma value. A feed forward neural network trained via two layer Broyden Fletcher Goldfarb Shanno algorithm is used for model development. The models are evaluated on the basis of set of performance indicators, namely, Nash–Sutclife Efciency, Root Mean Square Error, Variance and BIAS. A comparative assessment has also been made using these indicators for models developed, through data-set containing gauge discharges, only and the data-set fused with satellite-derived SCA. In particular, the current study concluded that the efciency of ANN-based streamfow estimation models developed for mountainous catchments could be improved by integrating the SCA with the gauge discharges.

3

Influence of afforestation on water regime in Jizera Catchments, Czech Republic

Romanowicz R.J., Kulasová A., Ředinová J., Blazková S.D.

Acta Geophysica

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2012

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Vol. 60, no. 4

1120-1142

EN

This paper studies the influence of afforestation on the water regime in two catchments in the Jizera Mountains that are similar in size and altitude but have different afforestation pattern. In this paper a range of different modelling tools is used to establish whether the differences in catchment water regime can be quantified and attributed to differences in catchment characteristics. Frequency analysis of low and high flows and a number and duration of flows over a threshold value are used to look for the differences in flow regime in both catchments. Low flow conditions are modelled using the Wittenberg nonlinear store approach. A rainfall-runoff process is modelled using a Data Based Mechanistic approach. The results indicate that the differences in the catchment response to external climatic factors outweigh the influence of land use apart from the low flows, where the changes in the response might be attributed to afforestation.

4

Zasady i środki opóźniania odpływu powodziowego dostosowane do zagospodarowania przestrzennego

Lenar-Matyas A., Łapuszek M.

Czasopismo Techniczne. Architektura

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2009

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R. 106, z. 2-A

75-81

PL

W ostatnich latach obserwuje się wzrost przepływów maksymalnych, których przyczyną są zarówno zmiany klimatyczne, jak i działalność człowieka na obszarze zlewni. Dotychczas problemy powodzi rozwiązywane były lokalnie. Często skutkowało to zagrożeniem terenów leżących poniżej, a także miało negatywny wpływ na środowisko naturalne. Jako odpowiedź na zainteresowanie proekologicznymi działaniami inżynierskimi opracowano metodę "Opóźnianie Dynamiczne". Jej celem jest ochrona przed powodzią za pomocą małych budowli lokowanych na terenie całej zlewni.

EN

In the recent years the significant increase of amplitude of extreme floods are observed, they are due not only to the climate changes but as well to the human activities in the river basins. Traditionally flood problems were mono-objective and turn to the local flood protection. With growing attention of ecology as well as flood protection arose the "Dynamic Slow Down" concept. DSD aims at solving flood issue in the scale of the whole catchment by the increase of its retaining capacity, wherever possible.