Wednesday 25 Jan 2017
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Delta Dynamics

 

Intra-annual inundation pattern in the Yellow River Delta derived from daily EO data of 2013

The goal of a study published by Kuenzer et. al 2015 is to demonstrate the potential of intra-annual time series analyses at dense temporal, but coarse spatial resolution for inundation characterization in river deltas. A complex processing chain of water surface derivation on a daily basis allows the generation of intra-annual time series.

Observation of land cover dynamics

The land coverage of the Yellow River Delta was observed as very dynamic during the last decades (Fig.1). This is caused by strong change in usage of natural resources and change in the agricultural system. The land cover map of 1979 displays a mainly untouched Yellow River Delta. After settlement foundation of Dongying city in 1983 the Delta region started to change due to population and settlement groth, river relocation, and intensification of usage of the land surface around the city of Dongying. Just from visual interpretation one can see (Fig.1) that the change is quite strong and fast - documented by classification of 4 time steps of Landsat imagery of the last 35 years.

 

Observation of water surface dynamics

The water coverage of the Yellow River Delta was observed since 2005 using SAR satellite imagery. Water surface maps, so-called "watermasks" were processed from SAR data and combined to inundation frequency maps for single years. The colors in Fig. 1 and Fig. 2 display the number of observations used for the inundation frequency map - blue indicates temporarly to permanently inundated areas, whereas red indicates that this part was covered by water only once (orange twice, yellow 3 times).

Observation of shoreline dynamics

The coastline of the Yellow River Delta was observed as very dynamic during the last decades (Fig.1). This is caused by high sediment inflow rate of the upstream river and by relocation of the river bed in the delta and river mouth relocation. Remote sensing data from all Landsat satellites were used to derive the Yellow River Delta coastline between 1976 and 2013. During almost four decades of available satellite imagery the Yellow River relocated three times (Fig. 2) – mainly by anthropogenic control of the river.

Observation of aquaculture development

The aquaculture development in the Yellow River Delta can be observed from remote sensing data analyses. Classification of Landsat imagery from 1995 and 2010 reveals large area changes of land use at the northern and southern coast of the Yellow River Delta (Fig. 1). In 2010 aquaculture ponds cover a four times larger area compared to 1995 (Fig. 2). Furthermore, water reservoirs and brine ponds were constructed. Intensification of land use at the coast in this region could be an indicator for settlement development – aquaculture and brine ponds provide food (fish) and salt for a growing population.

Observation of current changes in the Yellow River Delta

The Yellow River is undergoing rapid natural and especially human induced changes. During the field campaign in October 2013 a special focus was on identification of areas currently undergoing significant changes, such as preparation of land for new built up areas, construction of aquaculture and dykes, creation of new oil or gas pumps and extensive building of new houses. The photos below show some examples of current human activities in the Yellow River Delta area observed during the field campaign in October 2013.

 

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