Limnological Concept Gesäuse Phase II

This study presents phase II of the two-phase project management for the creation of a Limnological concept for the Gesäuse National Park. The basis for the drafting of the concept is the 6(2) of the National Park Ordinance, which states: The National Park Administration has to draw up a limnological concept and implement it within the framework of fisheries control. On the basis of this concept, the conservation of natural biodiversity and genetic variability, as well as the progress of the hemic animal population, will be ensured and promoted. Already for the processing of phase I of the limnological concept Gesäuse was divided into two investigation areas in which very different actual conditions and requirements for measures exist due to the strongly different proximity of nature or anthropogenic preload. The areas can be characterised as follows: — Investigation area 1 (UG 1): Enns between Lauferbauern and Gstatterbodenbrücke (approximately 6.7 km), Johnsbach from the tunnel in Johnsbach to the mouth of the Enns (approximately 4.7 km) of natural water character, predominantly unmounted or in dismantling as part of the EU-LIFE project. The naturalness of the water is comparatively high here; however, the 9 km long free flow route between the entrance of the Gesäuse and the Gstatterboden storage space also exhibits anthropogenic impairment as a result of spill-water discharges of the power plants at the two feeders Sölkbach (since 1978) and Salza (since 1949). Due to the surge operation of these power plants, the discharge behaviour of the Enns was significantly changed. Even in the Gesäuse, water level fluctuations of up to 20 cm per day (up to about 40 cm when the two spill amplitudes are superimposed) can still be observed (Hohensinner et al. 2008). — Investigation area 2 (UG 2): Enns between Gstatterbodenbrücke and Disc Fishing Bridge west of Hieflau (approx. 8.1 km) severely impaired section of the river: Dam root, reservoir with weir system and subsequent expulsion line (KW Hieflau) The severe anthropogenic impairment of this section is almost entirely due to the congestion and the abstraction of water for the power plant; other hydraulic interventions or morphological changes, such as those prevailing on lowland rivers, play only a small role on the enns in the Gesäuse. Thus, the Enns in the Gesäuse was in a largely natural state until the construction of the Hieflau power plant and the weir near Gstatterboden in 1953. Since commissioning, the Enns has been jammed on an approximately 1.5 km long route and diverted in the weir area, so that the drain is significantly reduced downstream of the weir on the approximately 7 km long discharge line between Gstatterboden and Hieflau (Kummerbrückenstrecke). The storage space has comparatively monotonous shore areas, on the left bank the wooded hem is largely missing. The route has so far been completed in summer (1 April 15. Oct.) dynamically endowed with up to 7.0 m/s, assuming a base dotation of 3.5 m/s. In winter there was no dotation of the expulsion line (Hohensinner et al. 2008). For Phase II, one sample of Enns and Johnsbach was now taken in area 1 and one sample at the Enns in test area 2. In particular, the following work was envisaged, the results of which are documented and discussed in this report: — Surveys of the macrozoobenthos and phytobenthos in Enns and Johnsbach, — Assessment of the ecological status of the two waters under the Water Framework Directive; and — Development of measures to achieve very good ecological status.本研究呈现的是为格绍伊泽国家公园（Gesäuse National Park）制定湖沼学概念（limnological concept）的两阶段项目管理的第二阶段工作。该概念起草的依据为《国家公园条例》（National Park Ordinance）第6条第2款，其中规定：国家公园管理部门须制定湖沼学概念，并在渔业管理框架内予以落实。依托该概念，可保障并推动自然生物多样性与遗传变异的保护，以及半水生动物种群（hemic animal population）的发展。 早在湖沼学概念第一阶段的推进工作中，格绍伊泽区域已被划分为两个调查区域——由于自然邻近性或人为负荷（anthropogenic preload）的差异极大，两个区域的实际现状与措施要求均存在显著不同。两区域特征如下： — 调查区域1（UG 1）：恩斯河（Enns）劳费尔鲍恩至加施塔特博登桥（Gstatterbodenbrücke）段（全长约6.7千米）、约翰斯巴赫河（Johnsbach）约翰斯巴赫隧道至恩斯河河口段（全长约4.7千米），均属自然水文特征水体，且大多未受人工改造，或正作为欧盟生命（EU-LIFE）项目的组成部分开展生态修复工作。 该区域水体自然性相对较高，但恩斯河在格绍伊泽入口至加施塔特博登水库间的9千米天然河道段，仍因两条支流策尔克巴赫（Sölkbach，1978年起运行）与萨尔察河（Salza，1949年起运行）上的电厂泄水而受到人为干扰。受此类电厂的调峰运行影响，恩斯河的水文节律已发生显著改变。即便在格绍伊泽区域内，仍可观测到每日最高达20厘米的水位波动（若两个电厂的泄洪幅度叠加，最高可达约40厘米）（Hohensinner等人，2008年）。 — 调查区域2（UG 2）：恩斯河加施塔特博登桥至希弗劳（Hieflau）西侧垂钓桥（Disc Fishing Bridge）段（全长约8.1千米），属于受严重干扰的河道区段：含拦水坝、带堰闸系统的水库及后续泄水管道（希弗劳电厂河段，KW Hieflau）。 该河段的严重人为干扰几乎完全源于电厂的筑坝拦水与取水，而诸如低地河流常见的其他水利工程干预或地貌改变，对格绍伊泽境内的恩斯河影响极小。直至1953年希弗劳电厂与加施塔特博登附近堰闸建成前，格绍伊泽境内的恩斯河基本处于自然状态。自投运以来，恩斯河在约1.5千米的河道段被筑坝拦截，并在堰闸区域改道，导致加施塔特博登至希弗劳间约7千米的泄水管道（库默尔布吕肯河段，Kummerbrückenstrecke）下游的径流量显著减少。该水库的岸线相对单调，左岸基本缺失林木覆盖的缓坡带。该河段在夏季（4月1日至10月15日）的流速动态变化可达7.0米/秒，假设基准流速为3.5米/秒。冬季时，泄水管道无水流补给（Hohensinner等人，2008年）。 针对第二阶段工作，本次在调查区域1内采集了恩斯河与约翰斯巴赫河的样本，并在调查区域2的恩斯河河段采集了样本。本次报告拟开展并记录讨论以下工作的成果： — 恩斯河与约翰斯巴赫河的大型底栖无脊椎动物（macrozoobenthos）与底栖藻类（phytobenthos）调查， — 依据《水框架指令》（Water Framework Directive）评估两处水体的生态现状，以及 — 制定旨在实现优良生态现状的修复措施。