The effects of mining, apart from surface subsidences and deformations, are forced flows of surface and underground waters, lasting many decades in the mining areas. Natural water flows should be ...restored by mining entities and/or their legal successors in the process of the mine closures. Such action is tantamount to a restoration of the previous state in the sense of repair of damage to the environment and surface infrastructure. Then, under natural water flows conditions, such mining areas may become flooded, often quite extensively. This paper describes a comprehensive method for flood threat assessment of artificially drained mining and post-mining areas after the restoration of natural water flows. The subject of this research is the surface of a single mine subsidence area. The term mine subsidence area (MSA) is defined as that part of the rock mass containing solid mineral deposits and the above surface affected by continuous and discountinuous deformation (as currently legally defined in terms of range and intensity). This method, together with simultaneous measurements of water levels at outflow places at the MSA boundary allows for an useful way of mapping the MSA surface. This has been developed to fully identify the true extent of mining-induced damage to the MSA aquatic environment. It introduces innovative hydromorphological elements of the MSA. These allow zoning of the MSA surface while taking into consideration future drainage works and/or projected mining subsidences inside the MSA. These spatial hydromorphological maps of the MSA identify the framework of permanent and occasional flooding and constitute the final result of this method. It is an universal tool for sustainable water management and quantitative evaluation for extraction of minerals.
•Mine subsidence area as primary subject of flood threat assessment.•Characteristic water stages at mine subsidence area outflow places as water management basis.•Relative elevation mapping of surface of single mine subsidence area.•Innovative hydromorphological elements as sustainable water management tools.
1. The keystone piscivore northern pike Esox lucius can structure fish communities, and models predicting pike-focused connectivity will be important for management of many waters. 2. We explored the ...ability of pike to colonize upstream locations and modelled presence-absence in lakes based on landscape features derived from maps. An upstream connectivity model (UC model) was generated using data from 87 lakes. We validated the UC model with retrospective whole-lake experiments involving introductions (n = 49) and extirpations (by rotenone) of pike (n = 96), as well as with the natural distribution of pike in lakes (n = 1365) within 26 drainage basin networks in northern Sweden. 3. The UC model predicted the incidence of pike in lakes with stream-connections with 95·4% accuracy, based mainly on a single variable, SV₅max, that measures the minimum distance found between 5 m elevation intervals (= maximum stream slope) along watercourses from nearest downstream source of potential immigrants. Recolonizations of pike in rotenone lakes generated a near-identical classification tree, as in the UC model. The classification accuracy of pike presence in the external validation procedure ranged from 88·7 to 98·7% between different drainage basins. Predictions of pike absence were not as accurate, due possibly to undetected introductions, but still lead to 86·6% overall accuracy of the external validation. Most lakes lacking pike, but misclassified as having pike based on low SV₅max, were isolated from downstream sources of pike by subsurface streamflow through bouldery areas (SSB). 4. Synthesis and applications. The variable SV₅max provide managers with a tool for revealing the location and severity of natural dispersal barriers to pike (and logically also barriers to other species with equivalent or less dispersal capacity). Because presented models only require map-based information, and have high predictive power, they may have the potential to be of fundamental use in predicting distribution of freshwater fish. These predictions may provide the means for prioritizing in risk assessment and control programmes to combat pike invasions, as well as contribute to determining a reference state of species incidence in specific lakes. Our results also point towards a possibility that, even where stream slope is low, long-term effective barriers may be designed that mimic natural SSB.
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