Search

In this study, a supervised artificial neural network (ANN) trained by back propagation (BP) algorithms was developed to predict the transpiration of poplar based on six input variables. Based on the transpiration characteristics of trees, a three-layer BP network was constructed with six input units and one output unit, Daily average temperature, relative humidity, photosynthetic affective radiation, wind speed, sunlight duration and the soil water content 50 cm below the soil surface were considered as the six input variables of the network, which primarily affected the transpiration of poplar. The prediction of daily transpiration of poplar in Heilonggang region, Hebei province was conducted. The research results indicated that R² equalled 0.9534 between measured values and predicted values. The maximum relative error, the minimum relative error and the average relative error were 16.85, 1.49, and 4.2%, respectively. The proposed model could describe the relationship between the daily transpiration of poplar, the meteorological factors and soil moisture conditions with a relatively high accuracy. The research results had potential values for the production and management in this polar stand. [ABSTRACT FROM AUTHOR]

Since a river system is a unidirectional network, the upstream influencing factors often interfere with those downstream. We quantify the effects of the TGD on the sediment exchange processes between the Yangtze River and Dongting Lake. Based on yearly sediment load data from 1981 to 2008, two multi-layer perceptron (MLP) models were constructed to predict the potential sedimentation in Dongting Lake without implementation of the TGD. The sediment discharge at Yichang station decreased from 622.5 to 61.1 Mt/year between 1981–1985 and 2003–2008, while the sedimentation in Dongting Lake reduced from 127.3 to 6.6 Mt/year. The MLP models indicate that only 27.9% of the decreased sediment load at Yichang station and 16.9% of that in Dongting Lake is caused by the TGD, while the rest is caused mostly by other upstream climate variations and anthropogenic impacts.EDITOR A. Castellarin; ASSOCIATE EDITORN. Ilich [ABSTRACT FROM PUBLISHER]