Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 7

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Anastomosing rivers were historically common around the world before agricultural and industrial development in river valleys. Presently, one preserved example of this type of river in Europe is the Upper Narew River in Poland. The uniqueness of the river determined embracing the 35 km-long section of its length and adjacent valley by formal protection as Narew National Park (NNP) and a Natura 2000 site. At present, the NNP Authorities are implementing a hands-off strategy focusing on maintenance of the processes. To assess the efficiency of such a policy, the current hydromorphological conditions of anastomosing river reach in NNP and the historical changes of the river planform at reach scale were recognized. The hierarchical framework tool (HF) was used for this purpose. Although current processes seem to prefer anastomoses maintenance, an analysis of historical river changes showed an accelerating pace of channel extinction. The anastomosing planform of the Narew was created through natural processes, but it has been maintained through a long history of human use and modification of the river system. The hands-off approach to direct channel management will most likely result in the further loss of anabranches, and hence the hands-on protection strategy seems to be a reasonable solution for protecting the NNP.
This study presents an application of the SWAT model (Soil and Water Assessment Tool) in an agricultural, coastal catchment situated in northern Poland, draining an area of 482 km2 (the Reda catchment). The main objective of this study was calibration and validation of the model against daily discharge and water quality parameters (bi-monthly total suspended solids [TSS], nitrate nitrogen [N-NO3] and phosphate phosphorus [P-PO4] loads). Calibration and validation were conducted using the SWAT-CUP program and SUFI-2 (Sequential Uncertainty Fitting Version 2) algorithm. The Nash-Sutcliffe effi ciency, which was set as an objective function in calibration of all variables, was equal for discharge to 0.75 and 0.61 for calibration and validation periods, respectively. For TSS, N-NO3 and P-PO4 loads NSE was equal to 0.56, 0.62 and 0.53 in calibration period, and 0.22, 0.64 and –1.78 in validation period, respectively. For the calibration period all the results are satisfactory or good, while for the validation period the results for TSS and P-PO4 loads are rather poor, which is related mainly to the lack of homogeneity between calibration and validation periods. These results demonstrate that SWAT is an appropriate tool for quantifi cation of nutrient loads in Polish agricultural catchments, in particular for N-NO3. The model can therefore be applied for water resources management, for quantifi cation of scenarios of climate and land use change, and for estimation of the Best Management Practices efficiency.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.