QUALITY INDICES OF WATERS FLOWING AWAY FROM CATCHMENTS OF SMALL RETENTION RESERVOIRS PLANNED IN THE KRAKOW REGION

Włodzimierz Kanownik, Włodzimierz Rajda
Department of Land Reclamation and Environmental Development, University of Agriculture, Cracow, Poland

ABSTRACT

The paper addresses the issue of the quality of water in uncontrolled watercourses covered by the small retention programme in the malopolskie province. Analyzed were the results of 12 quality indices assessments in waters flowing away from 6 partial catchments remaining under anthropopressure resulting from their typically agricultural, agricultural-settlement and settlement-agricultural management, including some forested areas. Small retention reservoirs have been planned in the analyzed catchments. Water samples for the analyses were collected at 11 dates in the cross sections of projected dams and water quality indices were tested using standard methods. Differences of some features influencing water purity class were demonstrated, particularly biogenic compound concentrations and their dependency on the management form dominant in the catchment. Results of former research conducted on small uncontrolled watercourses, mainly in the upland and mountain areas were also discussed.

Key words: small retention, catchment, anthropogenic factors, water, quality.

INTRODUCTION

Available surface water resources in Poland are among the smallest in Europe [23]. This poses a challenge for the authorities responsible for water management in individual regions of the country to develop and implement small retention programmes in order to improve the current state through water retention and collecting in partial catchments [5].

An agreement was signed in 2002 between the Minister of the Natural Environment, Minister of Agriculture and Rural Development and Directors of the Agency for Restructuring and Modernization of Agriculture and the National Environmental Protection Fund on cooperation in the field of small retention development and popularization and implementation of pro-ecological water retention methods [12]. Organizational forms were established and also terms of funding and support for the initiatives undertaken in this field. The programme follows the obligatory Directive 2000/60/EC of the European Parliament and the Council [2] called Water Framework Directive but also the Water Economy Strategy adopted by the Council of Ministers of the Republic in Poland in September 2005 [22]. The Directive priorities comprise among others an improvement of surface water quality, maintaining biodiversity (water biotopes directly dependant on waters), landscape diversification, activation and development of local communities.

In the malopolskie province, which on the scale of the whole country is distinguishable for the highest rainfall, compact soils and relatively small areas of partial catchments [1] but primarily for its diversified area relief, water reservoirs have been the standard endeavours planned within the small retention programmes. For various reasons such water reservoirs are necessary throughout the whole area of the province. Irrespective of their multiple functions they should store good quality water.

Organizational works on the Small Retention Programme for the Malopolskie Province were officially assumed by a substitute investor for budgetary tasks, i.e. the Malopolska Inspectorate of Land Reclamation and Water Facilities (MZUiUW) in Krakow. The basic assumptions and feasibility studies were made in 2004 by Hydroprojekt design office in Krakow, in cooperation with local self-government authorities and agencies of the Ministry of the Natural Environment. The Programme considers corrected initial designs of 69 small water reservoirs including 4 polders. Construction of the reservoirs was planned not only in typically agricultural areas but also in rural and suburban settlements and even in the urbanized areas in catchments of between several and several dozen km² [12]. The total water-storage capacity of the reservoirs is about 38 million m³, compensatory capacity 20 million m³, whereas the cost of their construction was estimated, according to prices of 2004, for about 994 million Polish zlotys.

Partial catchments constitute the initial stage of water resources formation and their quality. In these conditions surface waters are usually less liable to pollution but in case of  some designed reservoirs anthropogenic effects connected with the type of catchment management may prove important. Therefore analyses of water flowing away from small catchments, although so far not required, prove helpful and provide useful information about the quality of accumulated water is useful and necessary for the decision making process. Irrespectively of the reservoir size water eutrophication should be eliminated, especially as the Small Retention Programme following the recommendations of Directive 2000/06/EC [2] is a fundamental element of surface water protection. Specialists from the Regional Inspectorate of Water Economy voiced the need to conduct such research during MZMiUW meeting in Krakow on 28.05.2004 focused on the assessment of the programme developed by Hydroprojekt.

On a larger scale the research on water quality in small reservoirs was undertaken by the Department of Land Reclamation and Environment Development of the Agricultural University in Krakow in the nineties of the 20^th century. The research was continued in 2005 and 2006 on several watercourses in the Krakow region in order to prepare empirical material for the project entitled "Hydrochemical conditionings of small water retention reservoirs localisation in the Malopolska Region", which received funding from the Ministry of Science and Higher Education as a research and development project.

MATERIAL AND METHODS

The paper discusses the assessment results of 12 water quality indices, mainly biogenic compounds (Table 2) at 11 dates in 2005 and 2006. The analyses covered 6 uncontrolled streams included in the Programme [12] located in the Krakow region and within the city boundaries.

The Jaz and Sudół streams are characterized by agricultural-settlement catchments up to the cross sections of dams planned at Pychowice and Tonie villages. They are located on the south and north outskirts of Krakow (Fig. 2). Built-up areas are situated in the central part of the Jaz stream catchment, whereas in the Sudół stream catchment these areas are located mainly in its lower part (Fig. 1a, 1b). There are many roads in both catchments, their density is bigger in more compactly build-up areas.

The Serafa stream catchment in Bieżanów – a quarter of Krakow partially situated in the Wieliczka commune (Fig. 1d) is similarly managed. Moreover, small forested areas can be found in this catchment.

The catchments of the Sudół Dominikański in Węgrzce village and the Wilga stream to the cross section in Janowice village, beyond the Kraków city boundaries on the northern and southern side (Fig. 2) are characterized by settlement-agricultural management. In the first the settlement is more compact (Fig. 1c), whereas the second is characterized by dispersed development and few forested areas (Fig. 1e). Both have a dense road network but in the Wilga catchment the roads are more regularly spaced.

The Szczyrzawy stream catchment in Piekary village is also situated beyond the city boundaries (Fig. 2) in a farming region (Fig. 1f) with considerably fragmented fields, typical for the Krakow region.

The areas of the analysed catchments vary from 3.6 to 21.6 km². Average ground elevations, depending on the catchment range between 206 and 365 m a.s.l. and denivelations between 45 and 144 m. Also basic parameters of the projected reservoirs are diversified. The maximum depth of normal swelling (NPP) fluctuates from 1.7 to 9.5 m, and inundation area between about 9 to 22 ha (Table 1).

Quality indices of water collected for analyses at sampling points localised in the cross sections of the projected division walls were determined using standard methods [3]. Dissolved oxygen content was measured by an oxygen meter CO-411 on site, water reaction by CP-104 pehameter and electroconductivity by CC-101 Conductometer (Elmerton). The concentrations of chemical components dissolved in water were assessed at the Department of Land Reclamation and Environmental Development. The contents of PO₄^3-, NH₄⁺, NO₂^- and NO^-₃ were determined using continuous-flow colorimetry by FIAstar 5000 analyzer, Mn²⁺, Fe^2+/3+and Ca²⁺ concentrations by atomic absorption spectrometry in SOLAAR 969 apparatus (Unicam). Concentrations of sulphates (SO₄^2-) were assessed gravimetrically by means of barium chloride precipitation. The water quality was assessed on a five-degree scale according to the decree of the Minister of the Natural Environment of 2004 [20].

RESULTS

Analysis of the use and management of the studied catchments, conducted on the basis of topographic maps (Fig. 1) reveals a diversification of  the area pollution sources and provides bases for the assumption a hypothesis of different quality of the surface water flowing away. However, water quality may be also determined by other, point sources of pollution or brief events influencing the state of water environment, which usually are impossible to represent by mapping.

Mean concentrations of dissolved solids (DS) over the analyzed period and the dependant water electroconductivity (EC) in the Jaz, Sudół and Serafa streams (a, b and d) with catchment characterized by a considerable proportion of settlement, were higher than in the Sudół Dominikański, Wilga or Szczyrzawy streams (c, e and f) (Table 2) with more agricultural catchments (Fig. 1). Concentrations of biogenic components (NH₄⁺, NO₂^- and PO₄^3-) between the above mentioned catchments were similar, however their mean values and dissolved oxygen content unfavourably singled out also the water in the Sudół Dominikański stream (c) (Table 2). In case of this stream it might have been caused by not fully efficient performance of the local sewage treatment plant situated above the control cross section. It should be mentioned that control cross sections on the Jaz, Sudół and Serafa streams are situated within the city boundaries (Fig. 2), which is associated with more intensive catchment use.

Slightly higher concentrations of Ca²⁺ and SO₄^2- ions in water of the Jaz and Sudół streams, in comparison with the other objects (Table 2), may be connected with the basement complex structure.

The analysis of the values determined on all studied streams at the same dates (days) showed that the Wilga water reaction in Janowice and the Serafa in Bieżanów sometimes exceeded pH 9. Concentrations of nitrogen compounds were high in a majority of streams (Fig. 2), while phosphate concentrations in four streams occasionally exceeded the value of 1 mg·dm^-3. Ammonia concentrations in the Serafa, Jaz, Sudół and Sudół Dominikański (cross sections in Bieżanów, Pychowice, Tonie and Węgrzce) often exceeded 4 mg·dm^-3 reaching even 27 mg·dm^-3. Nitrite concentrations exceeded 1 mg·dm^-3 in waters of the Sudół and Sudół Dominikański (cross sections in Tonie and Węgrzce), whereas nitrate concentrations were exceeded in the Szczyrzawy, Sudół and Sudół Dominikański waters at cross sections in Piekary, Tonie and  Węgrzce, where 25 mg·dm^-3 was assessed.

Concentrations of dissolved oxygen in waters of the Serafa, Sudół and Sudół Dominikański were sometimes very low (below 4 mg·dm^-3) and only in the Szczyrzawy and Wilga it did not decrease below 7 mg·dm^-3.

Occasionally also high iron concentrations reaching 2 mg·dm^-3 were registered and  this value was even sometimes exceeded in the Wilga stream. Calcium concentrations in the Wilga water in Janowice and in the Serafa in Bieżanów were below 100 mg·dm^-3,while in the Jaz stream in Pychowice it was periodically higher than 300 mg·dm^-3.

Sulphate concentrations in two catchments (Tonie and Pychowice) seasonally exceeded 300 mg·dm^-3, whereas in the other streams they were below 200 mg·dm^-3. Manganese concentration values showed considerable stability and did not exceed 0.5 mg·dm^-3, except in the Sudół stream where it was seasonally above 1 mg·dm^-3.

Conducted investigations showed that water from the Szczyrzawy stream, whose catchment was primarily agricultural, was the least polluted one during the research period. A majority of indices placed the water in I, II or III purity class whereas only four from among the analysed indices (NO₂^- , PO₄^3-, Ca²⁺ and Fe^2+/3+) pointed to class IV (Fig. 2). Slightly greater pollution was detected in the Wilga stream water in Janowice, where registered pH values and Fe^2+/3+ ion concentrations classified it to V purity class (bad water), phosphates  to class IV whereas concentrations of the other indices did not exceed limit values for III water purity class (Fig. 2). Relatively low values of indices in two above mentioned streams resulted from comparatively small anthropopressure. A major part of the Szczyrzawy catchment is used as farmlands, whereas the Wilga catchments to the cross section in Janowice consists of  farmlands with strongly dispersed development and some forest areas.

From among the analysed streams, the Sudół was the most polluted in Tonie cross section on the boundaries of Krakow. Concentrations of six indices: NH₄⁺, NO₂^-, PO₄^3-, SO₄^2-, Mn²⁺ and O₂ placed its water in V purity class, four indices in IV class and two in III class (Fig. 2).

High values of the analysed indices were also registered in the Serafa in Bieżanów cross section. Water in the Serafa stream was classified in class V, as was determined by four indices (pH, NH₄⁺,PO₄^3- and dissolved oxygen content in water), whereas the other four (electroconductivity, dissolved solids, NO₂^- and Fe^2+/3+) allowed to classify it in class IV (Fig. 2). The reason may be compactly built-up city housing areas and  irregular water supply and sewage disposal in the area of this catchment.

DISCUSSION

Former research demonstrated (Table 3) that similarly as shown in the present paper, surface waters in small catchments, only partially managed for settlements, in the upland and mountain areas of the Malopolska Region are more subject to pollution than in extensively used typically agricultural catchments [10,14,15,17]. Therefore water quality in watercourses with settlement catchments the more unfavourably compares with headwater part of the Ryczanka stream catchment in Rzyki village in the Small Beskid Mountains [19], which is forested almost in 100% or with the water from forested partial catchment of the Trybszanka stream in Trybsz village in Polish Spisz Region [4], which are situated in conditions close to normal. However, even in these catchments, due to nitrate concentrations [4], suspended solids and pH [19], water quality was in III class of purity, according to the standards of 2003, and even in so called "non-class" waters.

Also research conducted in Chwiszcza and Perebel catchments [6] revealed that concentrations of individual mineral compounds depend on the catchment management. The lowest concentrations were registered in water flowing away from forest grounds, higher in outflow water from grassland and the highest in the water from ploughlands. Other investigations conducted in the mountain areas [10] demonstrated that water pollution was heavier in a cross section of a settlement catchment below Trybsz village in comparison with the cross section above the settlement area (Tab. 3). Ostrowski et al. [9] obtained similar results in their research conducted on the Wieprzówka stream flowing through urbanized area of a major Andrychów town (Table 3).

Former research revealed that pollution of the Sudół stream waters [13], where a construction of a  retention reservoir has been planned according to the Small Retention Programme for the Malopolskie Province [12], was increasing along the watercourse with changing type of the catchment management and growing anthropopresure. In this stream relatively most favourable indices characterized water in rural part of the catchment. Worse water quality indices were registered in the suburban, settlement part of the catchment and the worst in the end part of the watercourse in the city of Krakow. Skorbiłowicz noted a similar relationship on a lowland Orlanka river, where electroconductivity and ammonium, nitrate, phosphorus and potassium [21] concentrations were increasing visibly along with the river course and growing anthropopressure. Worsening indices were apparent in the Sudół stream also in the cross sections situated immediately below two operating wastewater treatment plants, which may evidence they not fully efficient performance [13].

Analyses conducted in 1998–2001 revealed also that factors connected with settlements, such as population number, number of buildings or flats per area unit, degree of built-up area, proportion of ploughlands in total area, stocking density and the amount of mineral and organic fertilizers have a significant and statistically confirmed effect on concentrations of some chemicals and some physicochemical characteristics of the waters flowing away from the catchment [16]. Research has shown that low water quality in small catchments under the pressure of the above mentioned factors were usually determined by high concentrations of NO₃^-, NH₄⁺ and PO₄^3- [10], NO₂^- and low content of dissolved oxygen [15]. Other research shows that beside these indices water quality was also determined by Mn²⁺ and BOD₅ concentrations [14, 17]. On the other hand, in water from typically agricultural and extensively used catchment, although no exceeded PO₄^3- concentrations were registered, but high concentration of NO₃^- [4] and suspended solids but low content of dissolved oxygen [15]. It was also found that in some partial upland and mountain catchments suspended solids were the factors disqualifying water [9]. Their high concentrations in these conditions might have been connected with considerable erosion potential.

CONCLUSIONS

1. Water quality in the analysed watercourses was diversified considering individual indices depending on the catchment type, but five of the six watercourses had water in V purity class, i.e. bad quality, whereas only in one, with predominantly agricultural catchment management, water was in class IV meaning unsatisfactory quality.

2. From among 12 assessed indices, between two and six indices classified the waters of five watercourses to class V, whereas in two watercourses none of the analysed indices were assessed within the limits  permissible for water in I purity class.

3. Relatively better water quality, in comparison with agricultural-settlement catchments with more compact settlement, was assessed in watercourses of agricultural and settlement-agricultural type with dispersed development. Worse water quality occurred in catchments situated closer to or  in the city area, which is connected with anthropogenic impacts.

4. In view of the obtained results and requirements of Directive 2000/60/EC and Water Management Strategy analyses of water quality in small watercourses, especially covered by the small retention programme, seem necessary. They may support decisions concerning the localization of water reservoirs and enforce activities aimed at restricting a negative impact of anthropogenic factors on water resources and improvement of water supply and sewage disposal in the catchment area.

ACKNOWLEDGEMENTS

The work was financed by the Ministry of Science and Higher Education in the framework of the Scientific Project No R12 001 02.

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Accepted for print: 22.06.2010

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