『Abstract
Surface runoff and associated erosion processes adversely affect
soil and surface water quality. There is increasing evidence that
a sound understanding of spatial-temporal dynamics of land use
and management are crucial to understanding surface runoff processes
and underpinning mitigation strategies. In this review, we synthesise
the effects of (1) temporal patterns of land management of individual
fields, and (2) spatio-temporal interaction of several fields
within catchments by applying semivariance analysis, which allows
the extent and range of the different patterns to be compared.
Consistent effects of management on the temporal dynamics of surface
runoff of individual fields can be identified, some of which have
been incorporated into small-scale hydrological models. In contrast,
the effects of patchiness, the spatial organisation of patches
with different soil hydrological properties, and the effects of
linear landscape structures are less well understood and are rarely
incorporated in models. The main challenge for quantifying these
effects arises from temporal changes within individual patches,
where the largest contrasts usually occur in mid-summer and cause
a seasonally varying effect of patchiness on the overall catchment
response. Some studies indicate that increasing agricultural patchiness,
due to decreasing field sizes, reduces the catchment-scale response
to rainfall, especially in cases of Hortonian runoff. Linear structures
associated with patchiness of fields (e.g. field borders, ditches,
and ephemeral gullies) may either increase or decrease the hydraulic
connectivity within a catchment. The largest gap in research relates
to the effects and temporal variation of patch interaction, the
influence of the spatial organisation of patches and the interaction
with linear structures. In view of the substantial changes in
the structure of agricultural landscapes occurring throughout
the world, it is necessary to improve our knowledge of the influence
of patchiness and connectivity, and to implement this knowledge
in new modelling tools.
Keywords: Surface runoff; Land use; Land management; Patchiness;
Connectivity』
Contents
1. Introduction
2. Materials and methods
3. Within-field seasonal patterns in surface runoff generation
potential
3.1. Soil bulk density
3.2. Soil sealing
3.3. Surface roughness and detention storage
4. Catchment-scale interaction between patches, patchiness and
surface runoff response
4.1. Effects of field size
4.2. Effects of spatial organisation of land-use patches
4.3. Effects of linear structures
5. Conclusions and summary
Acknowledgements
Appendix A. Concept and terminology of semivariances
References