Experimental study on spatial and temporal variability of microtopography

The spatial and temporal variability of microtopography influences obviously the basin irrigation performance. Based the observation of surface relative elevation(SRE) from some typical fields, the effect of cultivation and surface irrigation on the spatial and temporal variability of microtopography at different field-geometry is evaluated by means of statistical methodology. Results indicate that the mechanical cultivation and building of border dikes have significant effects on both overall distribution of microtopography and spatial distribution of SRE for precise land-leveled, while surface irrigation, to a certain extent, makes an impact on the spatial distribution of SRE, but small effect on the overall distribution of microtopography. For small fields, the effect of cultivation and surface irrigation on the spatial variability distribution of microtopography could be more evident, in which the building of border dikes and inflow rate per unit width are two main factors to affect the variation of microtopography for precise land-leveled. For big fields, except the factors above mentioned, the negative function of dints remained by the mechanical farming on microtopogaraphy should also be considered.