**1. Introduction**

Water movement in the landscape is a complex process, consisting of many connected and interacting processes at various spatiotemporal scales. These include processes on the level of soil aggregates, which affect infiltration and the ability of soil to hold water. Formation of macropore connectivity and surface channels, which affect surface and subsurface runoff.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Bedrock weathering and transportation processes affect redistribution of clay and nutrients. Organic matter in the soil profile and in the landscape feeds back to water movement and storage in the ecosystem. Many of these processes are affected by plants and soil biota, such as aggregate formation, creation of a porosity network, water intake by plants, or interception of rain by vegetation. Water enters the ecosystem by rainfall and leaves it by runoff and evapotranspiration. In the ecosystem, water can be stored in vegetation and in soil. The previous research shows that the ability of soil to store water is closely related to storage of soil organic matter (SOM) [1]. During ecosystem development, a vegetation cover develops, which reduces water input to the soil by interception and increases water loss by transpiration, but reduces evaporation from open soil surfaces. Vegetation also produces litter and root exudates, which are important for the activity of soil biota. Soil biota, which mostly directly or indirectly feeds on plant products, affects aggregate formation, storage of SOM, and distribution of SOM in the soil profile. Certain types of plants promote the activity of specific assemblies of soil biota, which affect certain patterns of SOM storage and distribution in soil. Plants with a conservative growing strategy promote a soil community that causes no or little bioturbation, which results in a thick litter and Oe layer on the soil surface. On the contrary, fast-growing plants promote intensive bioturbation by soil fauna and the formation of a deep A organo-mineral soil horizon [2–5]. This affects overall SOM storage [6, 2], which very likely affects water storage in soil as well [1]. Plants affect water movement in the system also by other means, such as by a different degree of interception and fate of water trapped by interception or different water consumptions and transpiration rates. Although all of these parameters have been intensively studied, we have only little information about how individual plant traits that affect SOM behavior in the soil relate to various parameters determining water storage and movement in the ecosystem. These interactions have been intensively studied in terms of the relationship between soil development and SOM storage, and although there is a general understanding that SOM may be closely related to soil-water, much less is known about factors and mechanisms affecting the water regime development during ecosystem development.

The aim of this contribution is to describe processes that affect the development of the water regime at post-mining sites after open-cast coal mining near Sokolov based on the extensive study of chronosequences at these sites. In addition, the idea of constructing isolated, controlled micro-catchments that would allow the investigation of these processes on various

Changes of Water Budget during Ecosystem Development in Post-Mining Sites at Various…

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As already explained, the development of a water regime can be divided into two parts: the development of soil, which stores water in the ecosystem, and the development of vegetation, which is an important consumer of water. However, vegetation also determines many transportation processes, which affect movement of soil between ecosystem compartments and surroundings, and directly or indirectly determines soil-forming processes. In this chapter, we will follow the formation of soil aggregates and their role in water retention, followed by the development of the whole soil profile and, finally, the development of vegetation and its

Soil aggregates are secondary particles formed through the rearrangement and cementation of primary mineral particles with SOM [10]. They are often grouped by size into macroaggregates (250–2000 μm) and microaggregates (53–250 μm) [11–13]. A highly influential model on the formation of aggregates was published by Tisdall and Oades [14] that was later modified by Oades [15]. Based on these models, it is now commonly accepted that macroaggregates form first, mainly by the entanglement of particles by fungal hyphae and roots (temporary binding agents) and around fresh particulate organic matter (POM) inputs. When these temporary binding agents and the POM in macroaggregates decompose into fragments, coated with mucilage produced during decomposition, they become encrusted with clay particles and thus form the nucleus for microaggregates within macroaggregates [11]. As a consequence of this "aggregate hierarchy," macroaggregates contain more C and higher amounts of labile C as compared to microaggregates, where SOM is more processed and regarded as relatively stable over longer periods of time. However, because of the higher lability of macroaggregates, the stability of microaggregates (contained within macroaggregates) depends to some extent on the turnover of macroaggregates. Apart from the earlier mentioned roots and fungal hyphae, factors generally positively influencing the formation and stability of aggregates are soil bacteria, producing extracellular polymeric substances, thereby cementing soil particles predominantly in microaggregates [14, 15], and the soil fauna, especially earthworms, forming stable casts and exerting pressure on the walls of their burrows, thereby compacting the soil [13, 16]. At initial post-mining sites, the clay content is another crucial factor as it forms the backbone of stable microaggregates [16]. At post-mining sites, overburden can be formed by clastic material, such as sand or gravel, but often it is deposited in the form of less consolidated material, such as shales, madstones, or stones [17, 18]. Weathering of this material and a gradual increase of the clay content is an important step in soil aggregate

levels, from soil aggregates to the landscape scale, is presented.

**2.1. Microscale processes of aggregate formation and porosity**

**various spatiotemporal scales**

role in soil profile development.

**2. Water regime development in chronosequence studies across** 

Mining and open-cast mining cause large disturbances to ecosystems. Most of the affected ecosystems are completely erased, either excavated or buried under overburden, which usually substantially differs from well-developed soils. In addition to texture, the hydrophobicity of the substrate [7], lack of macropores, soil compaction, and sometimes salinity are factors that can affect soil conditions, particularly the soil-water regime [8, 9]. The study of ecosystem development at these sites has a large practical impact. Post-mining sites also represent locations that have a great potential to study these processes. One of the reasons that make these sites suitable for the study of ecosystem development is the presence of sites of various ages, so-called chronosequences, where ecosystem development can be studied by comparing individual parameters or processes on sites of different ages. This approach, called also spacefor-time substitution, allows the study of long-term processes in a very short time. Despite its clear advantages, this type of investigation has also its limitations, as each site develops in a specific trajectory, which may differ from the general chronosequence pattern. Another reason why post-mining sites are good systems to study successional processes is that these sites offer a combination of parameters that may not occur elsewhere and are suitable for large-scale landscape manipulations, which would be technically hardly possible or ethically questionable elsewhere.

The aim of this contribution is to describe processes that affect the development of the water regime at post-mining sites after open-cast coal mining near Sokolov based on the extensive study of chronosequences at these sites. In addition, the idea of constructing isolated, controlled micro-catchments that would allow the investigation of these processes on various levels, from soil aggregates to the landscape scale, is presented.
