Scholarly record

WATER RESOURCE AND ENVIRONMENTAL PROTECTION IN LAKE BADOVC

Sabri Avdullahi

Abstract

In recent years, the intern ational community has witne ssed incidence of climate variability and human ac tivities. In this study, will be treated water resources and environmental protection is the catchments area of Lake Badovc. The catchments area of the Lake Badovc has a size of 109 km² and the active storage volume of the lake is assessed to 26.4 Mill.m3. Around 28% of the total population of Municipality of Prishtina supply with drinking water from Lake Badovc. The knowledge of flows reaching the Lake Badovc is important for developing a water resources plan. Since no usef ul hydrological data was available for the study it was decided to obtain this information by m eans of hydrological modeling based on a rainfall-runoff computation. The hydrologic modeling system used, is HEC-HMS developed by the Hydrologic E ngineering Centre of the US Corps of Engineers. The model is designed to simulate the rainfall-runoff processes of catchments areas and is applicable to a wide range of geographic areas. Water samples are taken from two streams reach Lake Badovc and from the lake in three different depths (5m, 10m and 15m) at different locations. Concerning the environment impact more than 140 intervie ws were conducted and questionnaires filled in the period October-November for Mramor area, concentrating on the most important issues: building, water supply, wastewater disposal and west disposal. Key words: Lake Badovc, water resources, water supply, water quality, pollution I1TRUDUCTIO1 Many hydrological models have been developed to simulate and help us to understand hydrologic processes. The hydrol ogical models are used as a watershed storm water management tool to provide a direction to utilize natural water resources effectively and beneficially. The period from about 1960 to 1975 was the era of “hydrologic modeling”, in which mathematical descriptions of fluvial processes were developed and incorporated into hydrological models [1]. 11th International Multidisciplinary Scientific GeoConference SGEM2011 www.sgem.org International Multidisciplinary Scientific GeoConference SGEM 2011 978 CATCHME1T AREA OF LAKE BADOVC The catchment area of Badovc Lake lies in the territory of the municipalities of Prishtina (~70%), Lipjan (~20%) and Novo Berdo (~ less than 10 %) [2]. The catchment of the Lake Badovc has a total area of 104 km². The ground elevations in the catchment area vary between 600 m.a.s.l. and 1200 m.a.s.l. 1. Water balance analysis The water levels in the lake are measured manually at regular time intervals. Apart from the lake water levels the dr inking water abstractions from the lake are measured continuously at the water treatment plant. 610 615 620 625 630 635 640 645 650 655 660 0 5 10 15 20 25 30 35 Reservoir storage capacity [x106 m³] Elevation [m.a.s.l.] Minimum operation level = 632 m.a.s.l. Maximum operation level = 650 m.a.s.l. Fig.1. Storage capacity curve of Lake Badovc The observed water levels in the lake can be combined with the lake storage capacity curve in order to calculate the changes of water volume in the lake. This can subsequently be combined with the measured drinking water abstractions from the lake to perform a water balance analysis of the Lake Badovc. The water levels in the lake can be related with the lake storage capacity curve in order to calculate the water volumes in the lake (figure 1). Based on the available measured data mentioned before, a water balance analysis was carried out for the years 2007 and 2008. The annual water abstractions of the years 2007 and 2008 exceed the corresponding inflows to the lake by amounts of 6.4 x10 6 m³ and 3.6 x106 m³ respectively. As a consequence the water level and the stored water volume in the lake decrease in this period. 2. Hydrological modelling In the catchment area of the Lake Badovc there are presently no operating gauging stations and therefore no records availabl e of discharges flowing into the lake. Information obtained during a site study in September 2009 indicates that the existing gauging stations were destroyed during the war. As in the case of the catchment of the Lake Batlava no useful hydrological data was available for the catchment of the Lake Badovc. Therefore it was decided to obtain the information required by means of hydrologi cal modelling based on a rainfall-runoff computation [3]. Also here the hydrologic modelling system HEC-HMS from the Hydrologic Engineering Centre of the US Corps of Engineers was used. 11th International Multidisciplinary Scientific GeoConference SGEM2011 www.sgem.org Hydrology and Water Resources 979 2.1. Digital terrain model With the advent of geographic information systems (GIS), digital terrain models have been used to delineate drainage networks and watershed boundaries, to calculate slope characteristics, to enhance distributed hydrologic models and to produce flow paths of surface runoff [4] [5]. In the course of the study two main sources of data were identified and found suitable for the DTM. Raw data from a recent laser scanning with 10 m raster size was obtained from the Kosovo Cadastral Agency. The second data source consisted in older topographic maps in scale 1:25.000 with contour lines in 10 m intervals. In the areas of the catchment were laser scan data was missing or the data was inconsistent the contour lines of the topographic maps were digitised. 2.2. Basin model The basin model of the Lake Badovc was created using the additional software package HEC-Geom., which is a geo-spatial hydrologic modelling extension for ArcGIS. Basically, HEC-GeoHMS allows to process spatial information, to document watershed characteristics, to perform spatial analyses, to delineate sub-basins, and to create inputs for hydrologic models [6]. The first step for creating the basin model is the processing the terrain data. The resulting data sets are used as spatial database for the study. The delineation of streams and sub-basins used in the hydrologic model of the Lake Badovc is shown in figure 2. Fig. 2. Sub-basins of the catchment area of the Lake Badovc For all sub-basins the following methods for calculating the losses (interception, infiltration, storage, evaporation), transf orm (runoff of excess precipitation) and base 11th International Multidisciplinary Scientific GeoConference SGEM2011 www.sgem.org International Multidisciplinary Scientific GeoConference SGEM 2011 980 flow (sustained runoff of prior precipitation stored temporarily in the watershed) were used: • Loss method: Deficit and constant loss • Transform method: SCS Unit hydrograph • Base flow method: Consta nt monthly base flow 2.3. Meteorological model The rainfall station Mramor lies inside the catchment of the Lake Badovc. The rainfall station Prishtina is also located near the area of study. Unfortunately no rainfall data could be obtained for these two rainfall stations. Concerning the values of evapotranspira tion needed for the hydrologic modelling the same considerations apply as in the modelli ng of the catchment of the Lake Batllava. The monthly values of evapotranspiration used in the hydrologic model are given in table 1. Table 1. Monthly average values of evapotranspiration catchment area Lake Badovc Month Monthly average Evapotranspiration [mm/month] Jan 1.8 Feb 7.2 Mar 22.2 Apr 49.4 May 95.4 Jun 139.7 Jul 175.7 Aug 144.7 Sep 76.7 Oct 44.3 Nov 19.2 Dec 4.4 2.4. Computation of inflows to Lake Badovc A calibration of the main parameters of the hydrologic model of the lake Badovc is not possible since no observed flows exist in the streams of the catchment. Because of their spatial proximity it is assumed that both catchments areas had similar rainfall conditions. Based on these considerations the parameters of the Batllava model were used for modelling the catchment area of the Lake Badovc. The computed total monthly flows of each main sub-basin and the total catchment of the Lake Badovc are presented in figure 4 show a comparison between total monthly inflows to the Lake Badovc computed with the hydrological model and calculated from the water balance analysis. The results in figure 4 show significant differences between the computed inflows to the Lake Badovc and the values calculated from the water balance anal ysis. Especially the values in the first half of 2007 and in the winter months of 2008 do not match. In both years considered the computed annual inflow to the Lake Badovc far exceeds the value calculated from the water bala ncing. Assuming that the modelled inflows are reliable, the following reasons for the low calculated inflows from the water balancing can be given: • Stream flows inside the catchment are intercepted before reaching the lake 11th International Multidisciplinary Scientific GeoConference SGEM2011 www.sgem.org Hydrology and Water Resources 981 • Additional water abstractions from the lake take place • Leaks in the lake are present and cause water losses Assuming that the computed annual inflows of 2007 and 2008 are reliable, the annual total inflow to the Lake Badovc under average rainfall conditions amounts to about 9.0 Million m³. -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 Jan.07Feb.07Mar.07Apr.07May. 07 Jun.07Jul.07Aug.07Sep.07Oct.07Nov.07Dec.07Jan.08Feb.08Mar.08Apr.08May.08Jun.08Jul.08Aug.08Sep.08Oct.08Nov.08Dec.08 Monthly total inflow to the reservoir [x10 6 m³/month] Calculated from water balance analysis Computed with hydrological model Fig.4. Monthly total inflow to the Lake Badovc 2007 and 2008 3. Water quality Lake Badovc Two streams reach Lake Badovc in the Mramor area. In the lake, water samples are taken at different locations and results are summarised in table 2. Chemical parameters, for which analyses were done, are in general in the acceptable range for raw water for water supply [7]. Also Lake Badovc is used as recreation area during summer. Bacteriological analyses should be verified during the next years [8]. Table 2 Water Quality of Lake Badocv Parameter A B C D Turbidity (NTU) 1.25 2.48 4.2 3.16 pH 8.7 8.6 8.61 8.62 NH4-N (mg/L) 0.03 0.05 0.02 0.02 NO2-N (mg/L) 0.058 0.038 0.033 0.052 NO3-N (mg/L) 1.2 1.7 1.6 1.9 Cl (mg/L) 22 16 18 19 KMnO4 (mg/L) 12.4 13.06 13.09 13.96 DO (mg/L) 4.6 4.1 4 5 Fe (mg/L) 0.36 0.037 0.376 0.075 Hardness (°dH) - - - - SO4 2- (mg/L) 41 40.7 41.7 40.7 PO4 3- (mg/L) 0.142 0.173 0.142 0.163 K (µS/cm) 375 376 379 380 Mn (mg/L) 0.087 0.111 0.063 0.082 Cu (µg/L) 0.063 0.052 0.016 0.069 Zn (mg/L) 0.237 0.168 0.159 0.167 Al3+ (mg/L) 0.02 0.01 0.01 0.03 11th International Multidisciplinary Scientific GeoConference SGEM2011 www.sgem.org International Multidisciplinary Scientific GeoConference SGEM 2011 982 4. Pollution sources Also regarding these important planning themes no up to date information was available for the catchment area. Assessing this situa tion, the study is prepared a questionnaire and organised a household survey in the Mramor area, concentrating on the most important issues. Around 140 interviews were conducted and questionnaires filled in the period October-November 2009 (table 3). Farmers informed that they concentrate on gr ains, e.g. wheat and corn as well as some vegetables. Fertilisers are occasionally app lied, as well as pesticides. However, estrogens were also detected in streams in areas with intensive agriculture [9].Overall the agricultural activities cannot be classified as intensive. Only three established restaurants were identified, but with more than 1.000 guest seats. There is no information on day-visitors dur ing the summer months. There is no piped water supply in the Mramor area or elsewhere in the catchment area. Around 80 % of the buildings have private wells, and the others receive their water from a tanker truck. Questions regarding water consumption could not be answered by the interviewees. The concentrations of estrogens in wastewater treatment plant influents and effluents were measured in several countries [10]. Two-thirds of the buildings have septic tanks and from the remaining buildings wastewater is discharged to the field. Table 3. Survey Badovc Mramor, Oct-1ov. 2009, summary all buildings Building Persons Water supply Wastewater Disposal Waste Disposal New Seasonal residents employees guests public well water tank septic tank dis. field container burning nature Private Houses / Buildings Total 127 15 0 654 0 0 0 110 0 82 30 0 10 14 87 Percent % 92 12 0 87 0 65 24 0 8 11 69 Shop/ Commerce Total 5 0 0 21 19 0 0 0 5 4 1 0 0 0 Percent % 4 0 0 0 10 20 20 0 0 0 Restaurant / Hotel Total 3 0 0 9 12 1100 0 3 0 3 0 0 0 0 0 Percent % 2 0 0 100 0 100 0 0 0 0 0 Other Buildings Total 3 0 0 0 17 160 0 0 3 3 0 0 0 0 0 Percent % 2 0 0 0 100 100 0 0 0 0 0 Grand Total 138 15 0 684 48 0 113 8 92 31 0 10 14 87 Percent % 100 11 0 0 82 6 67 22 0 7 10 63 11th International Multidisciplinary Scientific GeoConference SGEM2011 www.sgem.org Hydrology and Water Resources 983 DISCUSSIO1 A1D CO1CLUSIO1S The annual abstraction of drinking water from the Lake Badovc in the period 2006 to 2008 is average to about 11.5 Mill. m³/a. This value corresponds to the maximum treatment capacity of the Water Treatment Plant Badovc of 40,000 m³/d or 14.6 Mill. m³/a. The results of the modelling show that the minimum, average and maximum total annual inflows to the lake can be expected with around 6.3 Mill.m³/a, 9 Mill.m³/a, and 24.2 Mill.m³/a, (for low, average and high total annual rainfall). The active storage volume of the Lake Badovc is assessed to 26.4 Mill. m³. Based on these assessments following conclusions are realistic: • Average annual rainfall generates an inflow of only approx. 62% of the maximum abstraction rate for the water treatment plant • Assuming average annual inflow over a longer period and the maximum required abstration for the water treatment plant the storage capacity would be exhausted (minimum water level reached) within 4 to 5 years. • In the case of having a long period of extreme low rainfall the storage capacity would be already exhausted after 2 years. These conclusions are based on a limited amount data, but provide a first realistic assessment and an input for the determin ation of required additional raw water resources in order to satisfy the increasin g water demand. In order to obtain more precise results detaile d rainfall information is required, meaning records covering 20 and more years. The present average annual abstraction volum e cannot be increased, and must not be decreased. With a sequence of 2 very dry years, a temporary reduction of the average abstraction can occur. A detailed statistical evaluation of the “safe average abstraction volume” requires correct long term rainfall records from the catchment area. Increased bacteriological contamination has to be addressed as public health issue, because also Lake Badovc is used for recreation during summer. In general, buildings should have a septic tank and infiltration pit/soak away for the disposal of wastewater. Direct discharges to fields, drainage channels and water course should not be allowed any longer. For larger settlements, located close to the la kes, most probably a sewerage system will be required in the medium term. This definitely depends on the village/ area development plans and should be investigated in more detail, when the planning of a central water supply system starts. Consid ering these conditions, most likely in the Mramor area at Lake Badovc will become th e first area where a sewerage system will be needed. 11th International Multidisciplinary Scientific GeoConference SGEM2011 www.sgem.org International Multidisciplinary Scientific GeoConference SGEM 2011 984 REFERE1CES [1] Moore, I. D., Grayson, R.B., and Ladson, A.R.. Digita l terrain modelling: A review of hydrological, geomor phological and biological applications, Hydrological Process, 1991, Vol. 5, pp. 3-30 [2] Avdullahi S., Fejza I., Tmava A., Syla A., “Water Resources of Drini i Bardhe River Basin Kosovo” International Journal of Na tural and Engineering Sciences, Turkey, IJNES 2 (3): pp 105-109, 2008 [3] Alcamo J.; Flörke M., and Märker M., 'Future long-term changes in global water resources driven by socio-economic and c limatic change'. Hydrological Sciences Journal 52: 247–275, 2007. [4] Moore, I. D., Grayson, R.B., and Ladson, A.R.. Digita l terrain modelling: A review of hydrological, geomor phological and biological applica tions, Hydrologi cal Process, 1991, Vol. 5, pp. 3-30 [5] Saraf, A.K, Choudhury, P.R., Roy, B. Sarma, B., Vijay, S. and Choudhury, S. GIS based surface hydrological modelling in iden tification of groundwater recharge zones, International Journal of Remote Sensing, 2004, Vol. 25, pp. 5779-5770 [6] USACE User’s Manual, Geospatial Hydrologic Modeling Extension, HEC- GeoHMS, Version 1.1, U.S. Army Corps of Engineers Hydrologic Engineering Center, California, USA 2003, www.hec.usace.army.mil [7] Korça B, Jusufi S, Shehdula M, Bacaj M, Surface Water Pollution in Kosovo, Scientific Conference: Technical-Technol ogical Sustainable Development and Environment, Proceeding Book, pp. 43-49, 2002 [8] Cole, Thomas M. and Herbert H. Hannan. (1990). “Dissolved Oxygen Dynamics”, Reservoir Limnology: Ecological Perspectives. Kent W. Thornton, Bruce L. Kimmel, and Forrest E. Payne, eds., John Wiley& Sons, Inc., New York, NY. [9] Kolpin, D. W., Furlong, E. T., Meyer, M. T., Thurman, E. M., Zaugg, S., Barber, L. B. & Buxton, H. T. Phar maceuticals, hormones, and other organic wastewater contaminants in U.S. streams, 1999–2000: an ational reconnaissance, Environmental Science and Technology, 36(6), pp. 1202–1211, 2002 [10] Koh, Y. K. K., Chiu, T. Y., Boobis, A., Cartmell, E., Scrimshaw, M. D. & Lester, J. N. Treatment and removal strategies fo r estrogens from wastewater, Environmental Technology, 29(3), pp. 245–267, 2008 11th International Multidisciplinary Scientific GeoConference SGEM2011 www.sgem.org

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