{'fraction_non_alphanumeric': 0.020177562550443905, 'fraction_numerical': 0.0129136400322841, 'mean_word_length': 4.904761904761905, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Planning and effect evaluation for vegetative filter strips in water source area based on model simulation

Vegetative filter strip (VFS) is a new kind of ecological engineering measure for the control of nonpoint source pollution. For investigating the application of mathematical models in the planning and designing of vegetative filter strip, the vegetative filter strip hydrology and sediment transport model (VFSMOD) was used to analyze the effect of VFS' width and slop on the sediment load removal rate in Heihe water source area, thus determining the appropriate planning scheme of vegetative filter strip. Subsequently, the linear relationships between the unit load of TP, TN and unit sediment were used to estimate the watershed nonpoint source pollution load reduction efficiency of VFS. The results showed that the grass filter strips with width in the range of 3 ~ 5 m was advisable and should not be used on slopes with gradient of higher than 60°; when VFS was constructed on parts of sensitive riparian in the water source area, the incoming load of sediment, TP and TN could be reduced by 22.14, 12.66 and 14.60%, respectively. VFS could play an important role in the water quality protection of Heihe water source area.