The Pesnica catchment is defined as a 2th level hydrographic area (HGA II) according to the national classification of the hydrographic areas. It is a hydrographic sub-area of the Drava catchment (HGA I, 3.270,78 km2), belonging to the Danube river basin. With the total surface area of 540.8 km2 the Pesnica catchment represents 2.7 % of the Slovenian national territory. The total length of the watercourse network in the catchment is 1,884.9 km, with the Pesnica river length being 64.6 km.
The catchment is predominantly covered by agricultural land (65,9 %), followed by forests (26,4 %), and urban areas (6,8 %). The most conspicuous feature of the Pesnica catchment is a mosaic of meadows, small fields, vineyards, traditional orchards, forest fragments, small swampy valleys and dispersed settlements, characteristic for the dominant hilly landscape. The traditionally managed mosaic cultural landscape has a significant conservation value, resulting in relatively high proportion of area having a protection status (including Natura 2000). In contrary, the relatively narrow Pesnica river plain, reaching 2 km in its middle course and 4 km in its lower course, is dominated by a more intensively managed agricultural land. Majority of the land in the catchment is privately owned (81%).
The area of the catchment under Natura 2000 is 2,635 ha (4.9 % of the total catchment area) and the area under national or local protection status is 12,042 ha (22.3 % of the total catchment area). Natura 2000 areas completely overlap with the areas under national or local protection status.
The Pesnica catchment administratively belongs to 21 municipalities, including urban municipality of Maribor, and municipalities of Selnica ob Dravi and Duplek, which overlap with the catchment only narrowly at their edges. The total number of inhabitants of municipalities, excluding the latter three, is 291,440. Most municipalities are underdeveloped, relative to the Slovenian average: five rank in the 2nd quarter (including the urban municipality of Maribor), 11 in the 3rd quarter and five in the 4th quarter according to the national municipal development coefficient.
The Pesnica river originates in Austria and reaches the Slovenian border just about 4 km downstream from the source. After crossing the hilly landscape of Slovenske gorice, dividing it in two parts, it flows into the Drava river in the town of Ormož. It has a pluvio-nival hydrologic regime. Its specific runoff (9.7‒11.4 l/s*km2 at three measuring stations between 1971‒2000) is lower by more than half compared to the Slovenian average. Its average discharge between 1971‒2000 was 2.88 and 4.96 m3/s at two measuring stations in the lower course, with peak average discharges in March and November.
The Pesnica river has been extensively regulated in the past, which is why a large part of it is now in poor ecological condition. Photo: Tilen Basle
The slow flowing and historically meandering Pesnica river, that was regularly flooding, was restricting settlement and agricultural use of the valley. The watercourse and its floodplain were thus extensively regulated in the mid-20th century, by means of riverbed straightening and deepening, construction of weirs and dams, and melioration channels network. The valley remains largely unsettled, with few villages stretching out to the riverbanks, however, the novel conditions allow for intensive agriculture, characterized mainly by crop production. No areas of significant flood risk have been mapped as part of the national flood risk assessment according to Floods Directive (Directive 2007/60/EC) in the Pesnica catchment so far, however, the hydrological surveys in the catchment are deficient.
Extensive past hydro-morphological alterations and current maintenance works, rooted in the traditional flood control paradigm, water withdrawal, as well as runoff from the agricultural land present the main pressures to the Pesnica river. The result of these pressures is its poor ecological status in the upper course (18.7 km), and moderate in the lower course (45.9 km), as assessed according to the EU Water Framework Directive. Moreover, according to RCE assessment more than 55 % of the river is in need of extensive restoration measures and additional 31 % in need of moderate improvement.
However, despite extensive implementation of flood protection measures a few short stretches of the river have retained conservation value to the present day. The most downstream stretch of the Pesnica river, as well as one of its tributaries, the Slatinski stream, have the status of Natura 2000 (SI3000220 and SI5000011, and SI3000370, respectively). In addition to these, a few other stretches are also protected according to the national legislation, either as natural assets, ecologically important areas or protected areas.