WFD Cycle 2 river hydrology classification

This dataset is a subset of "WFD Classification Status Cycle 2" and contains classification data for hydrological regime. A river can only hold a healthy biological population if there is sufficient water and natural structures to support biological processes. Rivers with sufficient flows can also support human activities such as farming, drinking water supply and industrial processes. The hydrology assessment tool uses data on freshwater flows, physical modification and water abstraction to assess the health of a water body. The tool works by assessing a water body’s compliance category (freshwater inputs less abstraction amounts) against a score for flow compliance.
A water body cannot score high status if it is considered to be ‘heavily modified’ which refers to a river being modified from its natural state for human use. If a water body considered heavily modified scored high in the compliance and flow tests it would be automatically downgraded to ‘Supports Good’ status.
Flow, abstraction and physical structure data are used in combination to produce scores known as Ecological Quality Ratios (EQR). EQRs are used to produce a Hydrology classification (High, Supports Good, Good, Moderate, Poor, Bad) of the water body for Water Framework Directive (WFD) purposes. Attribution statement: © Environment Agency copyright and/or database right 2015. All rights reserved.

本数据集为“WFD 分类状态周期 2”的子集，包含水文状况的分类数据。若河流拥有充足的水量和自然结构以支撑生物过程，则其能够维持健康的生物种群。流量充足的河流亦能支持人类活动，如农业、饮用水供应及工业流程。水文评估工具通过淡水流量、物理改造及水提取数据来评估水体健康。该工具通过评估水体合规类别（淡水输入量与提取量之差）与流量合规评分的匹配度来实现。若水体被认定为‘严重改造’，即河流为人类使用而从自然状态改变，则其无法获得高等级评分。若被认定为严重改造的水体在合规性和流量测试中得分较高，则将自动降至‘支持良好’等级。流量、提取及物理结构数据相结合，生成被称为生态质量比（EQR）的评分。EQRs 被用于生成水框架指令（WFD）目的下的水文分类（高、支持良好、良好、中等、较差、差）。归属声明：© 环境署版权及/或数据库权利 2015。版权所有。