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1

Clarifcation of issues and long-duration hydrologic simulation SCS-CN-based proxy modelling

Aragaw Henok Mekonnen, Mishra Surendra Kumar

Acta Geophysica

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2022

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Vol. 70, no 2

729--756

EN

The aims of this paper are to (I) clarify some issues related to the popular rainfall–runoff SCS-CN (Soil Conservation Service Curve Number) methodology and (II) propose enhanced SCS-CN inspired models for simulation of long-duration (viz., bimonthly, monthly, seasonally, and annually) rainfall-generated runoff and compares its performance with the existing SCS-CN models and Mishra and Singh 1999 model. Issues of SCS-CN are: (a) both C (runoff coefficient) and CN (curve number) with P (rainfall) in contrast to that exhibited by field data, (b) F (infiltration) with Q (direct runoff), (c) Ia (initial abstraction) with S (potential maximum retention), and (d) CN that is also taken as an index of runoff potential. The performance of the proposed SCS-CN inspired models (M3-M8), the existing SCS-CN models (M1 and M2), Mishra and Singh 1999 model (M9), and a special case of M9 that hypothesizes that initial abstraction coefficient (λ)=0 (M10) are tested using rainfall–runoff data of four different agro-climatic river basins in Ethiopia. The performance of the models is evaluated using three statistical criteria involving NSE, RSR, and PBIAS. The resulting high NSE values and lowest RSR and PBIAS for the proposed models reveal that proposed models performed better to different (majority) duration datasets than the existing models. Similarly, the proposed models, when employed to the observed datasets of different timescales, performed satisfactorily in both calibration and validation for all watersheds, underlining the efficacy of the proposed models in field applications.

2

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

Wałęga A., Rutkowska A., Grzebinoga M.

Acta Geophysica

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2017

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Vol. 65, no. 2

363--375

EN

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.

3

Assessment of Retention Potential Changes as an Element of Suburbanization Monitoring on Example of an Ungauged Catchment in Poznań Metropolitan Area (Poland)

Mrozik K.

Rocznik Ochrona Środowiska

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2016

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Tom 18, cz. 1

188--200

PL

Rozwój miast skutkuje znacznymi zmianami użytkowania terenu i powiązań funkcjonalnych pomiędzy obszarami miejskimi i wiejskimi. Zmieniające się relacje pomiędzy użytkowaniem obszarów miejskich i wiejskich prowadzą do zmian jakości życia mieszkańców, środowiska i świadczeń ekosystemów, w tym zasobów wodnych. Zmiany te są najbardziej widoczne na obszarach podmiejskich. Różne scenariusze rozwoju obszarów zurbanizowanych w Europie oparte na założeniach IPCC wskazują niezależnie na ich dalszą ekspansję w granicach 0,4-0,7% rocznie, co jest wynikiem ponad dziesięciokrotnie wyższym niż rozwój jakichkolwiek innych typów użytkowania. Oznacza to, że nasilenie tego procesu będzie szczególnie widoczne na obszarach podmiejskich, w tym na znacznych obszarach Polski. Obserwowane intensywne przekształcania terenów użytkowanych rolniczo na tereny zabudowane i zurbanizowane zmuszają do zastanowienia się nad wpływem suburbanizacji na gospodarowanie wodami zwłaszcza w kontekście zjawisk ekstremalnych, z których w Polsce w ostatnich dwóch dekadach szczególnie dotkliwe okazały się powodzie w 1997, 2001 i 2010 r. Szczególnego znaczenia nabiera potrzeba monitoringu zjawiska suburbanizacji w kontekście jej wpływu na gospodarowanie wodą w zlewni rzecznej będącej zgodnie z zasadą IWRM podstawową jednostką planistyczną w planowaniu w gospodarowaniu wodami. Celem pracy była ocena możliwości zastosowania metody SCS-CN jako elementu monitoringu procesu suburbanizacji poprzez zwymiarowanie zmian w potencjalne retencyjnym niekontrolowanych zlewni rzecznych na terenach podmiejskich w miejskich obszarach funkcjonalnych (metropolitalnych). Szczegółowe analizy w pracy wykonano na przykładzie zlewni Skórzynki położonej w granicach gmin wiejskich Dopiewo i Tarnowo Podgórne i miasta Poznań stanowiących rdzeń Poznańskiego Obszaru Metropolitanego (POM) (określanego obecnie jako Miejski Obszar Funkcjonalny Ośrodka Wojewódzkiego) Ogółem według delimitacji zaproponowanej przez Wielkopolskie Biuro Planowania Przestrzennego POM obejmuje 45 gmin wraz z Poznaniem (w tym 15 miast powiatowych i 15 pozostałych miast). Do oceny zmian potencjału retencyjnego i opadu efektywnego wykorzystano metodę SCS-CN. Zmiany zagospodarowania terenu oceniono na podstawie mapy topograficznej z 1998 r. w skali 1: 10 000 oraz urban atlasu bazującego na zdjęciach satelitarnych SPOT5 o rozdzielczości terenowej 2,5m z roku 2007. Dane dotyczące gleb pochodziły z mapy glebowo-rolniczej w skali 1: 25 000 wykonanej przez IUNG w Puławach. Wszystkie analizy wykonano przy użyciu oprogramowania ArcGIS 10.0 firmy ESRI. Dane opadowe pochodziły ze stacji Poznań-Ławica. Dzięki metodzie SCS-CN wykazano dla zlewni Skórzynki w okresie 11 lat dla przeciętnych początkowych warunków wilgotnościowych spadek potencjalnej retencji (o 20%, tj. z 99 na 80mm) oraz wzrost opadu efektywnego (o 17%, tj. z 35 na 41mm) wyliczonego dla ekstremalnego zdarzenia opadowego odnotowanego 17.08.2010 r. Wykonane analizy pozwalają stwierdzić, że metoda SCS-CN jest użytecznym i pożądanym narzędziem monitoringu procesu suburbanizacji w niekontrolowanych zlewniach położonych w obrębie obszarów metropolitalnych w celu oceny zmian potencjału retencyjnego zlewni. Uzyskane wyniki mogą stanowić kryterium decyzyjne dla lokalnych władz we właściwym kreowaniu polityki przestrzennej, zwłaszcza w zakresie kształtowania zasobów wodnych oraz przeciwdziałania lokalnym powodziom i suszom.

EN

The development of the cities results in significant changes in land use and functional connections between urban and rural areas. The changing relations between the use of urban and rural areas lead to changes in the quality of the inhabitants’ lives, of the environment and ecosystem services, including water resources. Those changes are the most visible in peri-urban areas. Different scenarios of the development of urbanized areas in Europe based on the IPCC assumptions indicate their further expansion at 0,4-0,7% per year which is over 10 times higher score than any other land use. This means that the intensity of this process will be particularly visible in peri-urban areas, including considerable areas of Poland. The observed intensive transformations of arable lands into built-up and urbanized areas make one think about the influence of suburbanization on water management, especially in the context of extreme phenomena, out of which the most afflictive over the two last decades were floods in 1997, 2011 and 2010. Monitoring the process of suburbanization gains importance in the context of its influence on water management in the river catchment which, according to the IWRM principle, a basic planning unit are in water management planning. The objective of this paper was evaluation of the possibility of using the SCS-CN method as an element of monitoring process of suburbanization through sizing the changes in the in water retention potential of ungauged catchments on peri-urban areas of metropolitan areas. Detailed analyses were carried out based on the Skorzynka river catchment located within the rural communes of Dopiewo, Tarnowo Podgórne and the city of Poznań which are the nucleus of Poznan Metropolitan Area (PMA) (currently defined as the voivodeship urban functional area of Poznań). Altogether, according to the delimitation proposed by the regional planning office Wielkopolskie Biuro Planowania Przestrzennego (WBPP), PMA comprises 45 communes together with Poznań (including 10 cities – centres of district and 15 other small cities). To the assessment of potential water retention and effective precipitation the SCS-CN method was used. The changes in land use were estimated on the basis of a topographic map from 1998 at a 1:10 000 scale and the Urban Atlas based on satellite photographs from SPOT 5 satellite on the ground resolution of 2.5 m from 2007. Data on soil were obtained from soil and agricultural maps at a 1:25 000 scale performed by Institute of Soil Science and Plant Cultivation (IUNG) in Puławy. All analyses were performed using ArcGIS 10.0 software by ESRI. The information about precipitation based on the data from the climatic station of Poznań Ławica Thanks to using the SCS-CN method a 20% decrease of potential water retention (99 to 80mm) in the 11-years period for Skórzynka catchment in average antecedent moisture conditions (AMC II) has been demonstrated. Also, a 17% increase of effective precipitation (35 to 41 mm) calculated for extreme rainfall event observed on 17/08/2010 was shown. The conducted analyses allow to conclude that the SCS-CN method is a useful and desirable tool used to monitor the process of suburbanization in ungauged catchments located within metropolitan areas in order to assess the changes of potential water retention. The obtained data may be a decision criterion for local authorities in the proper creation of spatial policy, especially in the sphere of water resources management and preventing local floods and droughts.

4

Ocena wpływu zmian użytkowania terenu na odpływy wezbraniowe przy użyciu metody SCS-CS

Miler A. T.

Rocznik Ochrona Środowiska

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2012

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Tom 14

512--524

EN

Estimation of influence of land use changes to flood outflows from areas of the Roztocze Srodkowe and of the Krajenskie Lakeland were worked out basing on SCS-CN method. This method permits calculation from total rainfall a direct runoff as equivalent to effective rainfall. The original SCS-CN method in principle was worked out for catchments of cultivated areas. Present paper is focused on the idea of adaptation original method to forest conditions. The main parameter of this method - CN is a function e.g. of land use. The empirical values of parameter CNemp were calculated basing on hydro-meteorological data of flood outflows at representative catchments. The dependence between empirical value of parameter CNemp and his equivalent's value from original method is a basis idea of adaptation method SCS-CN to characteristics of investigated catchment. In consequence it gives then possibility to prognoses how the change of land use, e.g. forest stand reconstruction, afforestation, deforestation, change of field culture, significant change in infrastructure etc., will influence to flood outflows (change to water retention) at a representative areas (a quasi-homogeneous in relation to investigated catchment). The first analyzed catchment of the Krynica River (area 19.1 km(2), afforestation 49.3%) is representative for the,Tomaszow Lubelski Forest Division and quasi-representative to the Roztocze Srodkowe (Poland). The area of catchment is situated within the following units: macroregion - Roztocze, mesoregion - Roztocze Srodkowe; this area belong to IV Mazowiecko-Podlaska Land. On area of the Tomaszow Lubelski Forest Division predominate the rusty soils (42.65%) as well as the brown soils (26.51%). Associations of beech forests and oak-hornbeam forests predominate. Pine is the dominant species, covering 55.37% forested area, beech is found at 19.70%, oak at 11.07%, alder at 3.49%, fir at 3.24%, hornbeam at 1.73%, birch at 2.14% and larch at 1.19%, while other species constitute a highly valuable admixture in the biocenosis. On area of investigated catchment granulometric composition is following: loose sand 70%, loamy sand 15% and loamy sand on loamy gravel 15%. Average daily specific discharge (in investigation period 2009-2010) was on level 3.4 [1.s-1.km -2], and maximum to minimum suitably 17.2 to 1.0[1.s-1.km -2]. The second analyzed catchment of the river no. 17-86-1 is located in the III Wielkopolsko-Pomorska Land, the Two Krajenskie Lakeland District, the Wysoczyzna Krajenska mesoregion (Poland). The investigated catchment cover the area of 182.26ha; 174.02ha - 95% covered by forests, and 8.24ha - 5% arable land and meadows. The dominant soils are rusty soils (about 86% of catchment area) and similar. The dominant forest habitat types are: fresh coniferous forest (sign Bsw - in Polish standards) and fresh mixed coniferous forest (BMsw) - about 90% of catchment afforestetion area. Main species at afforestation area is ordinary pine (Pinus sylvestris L.) (93% of forest area). Average daily specific discharge (in investigation period 2004-2006) was on level 6.4[1.s-1.km -2], and minimum to maximum suitably 2.5 to 25.5[1.s-1.km -2]. The calculation were conducted using data of measuring rainy flood waves. The values of CNemp ware a base for introducing scenarios how changes of land use at investigation catchments are influencing to flood outflows (changing water retention).