01.

设计源起

Origin of design

西川原名“西干渠”，全段31公里，北起黄河南岸，往南最终流入郑州牟山湿地公园，是一条农田灌溉渠道。

Xichuan, an agricultural irrigation canal known as ‘Xigan Canal’ before, stretches for 31 kilometers from the south bank of the Yellow River to Moushan Wetland Park in Zhengzhou.

▼项目区位图，Project location map

近十年来，随着郑州国际产业园区的建设，水系规划被提上日程，结合郑州市中牟县雁鸣湖片区的陆续开发规划，西干渠所扮演的角色发生转换，在满足灌溉功能的同时，也被要求创造出能供市民娱乐休闲的活力空间，促进人与自然的融合。

结合区域总体规划，我们负责进行改造设计的“西川”，位于郑州市中牟县大孟镇，信王节制闸至逐鹿营之间，总长约2.1公里。这段改造段被定义为中牟县水系改造的示范段落，它的建成将为区域性水系改造，尤其是灌溉渠道改造，提供指引方向。

In nearly a decade, the city water system planning is on the agenda with the construction of Zhengzhou industrial park. The role of Xigan Canal has changed to better combining with the on-going development planning of the Yanming Lake area, Zhongmou County, Zhengzhou. Therefore, Xigan Canal is asked to both meet the requirement of irrigation function and create a recreation space for public entertainment and leisure, which can ultimately promote the fusion of nature and humankind.

Considering about the overall planning, Xichuan, restored and designed under our charge, is located between Xinwang check gate and Zhulu camp in Dameng Town, Zhongmou County, Zhengzhou. The reconstruction section with a total length of about 2.1 kilometers is defined as the demonstration section of water system reconstruction in Zhongmou County. Its completion will provide guidance for the improvement of regional water systems, especially irrigation channels.

▼郑州国际文化创意产业园分区水系规划(2015-2030年)，西干渠全段都被定义为景观水系，需要承担城市观景与滨水休闲功能

Water system planning for Zhengzhou International Cultural and Creative Industry Park (2015-2030). Xigan Canal is defined as landscape water system which functioned both as urban landscape and waterfront leisure

2.

场地现状

Site description

大孟镇属北温带大陆性季风气候，冷暖适中、四季分明，春季干旱少雨，夏季炎热多雨，秋季晴朗日照长，冬季寒冷少雪。全年平均气温14.2℃，平均降雨量616 毫米。境内有大小河流124条，分属于黄河和淮河两大水系。西干渠属黄河水系，水源为黄河灌溉引水，水量较少；渠道宽度约6米，深度约1.5米，基底为全硬质混凝土结构以提升灌溉效能。

改造段周边农田已大部分荒废，地势平坦，水体表面漂浮大量的农业生活垃圾、枯枝杂草等。渠道基本不具备水生态系统，自身净化能力较弱，水体总体呈富营养化趋势。

Dameng Town belongs to the north temperate continental monsoon climate with mean annual temperature of 14.2 ℃ and mean annual precipitation of 616 mm. It has moderate temperature and distinct seasons with dry spring, hot rainy summer, sunny autumn and cold winter with little snow. There are total 124 rivers in this area which belong to Yellow River and Huai River. Xigan Canal belongs to Yellow River water system, which water source is the irrigation and diversion of the Yellow River with a small water yield. The canal is about 6 meters wide and 1.5 meters deep, and its base is made of all-hard concrete structure for the aim of improving irrigation efficiency. The farmland around the reconstruction area is flat and has been largely abandoned, resulted in a massive number of agricultural household garbage, weeds and twigs floating on the surface of water. Hence, due to its weak purification capacity and generally eutrophic water body, the canal basically cannot function as a water ecosystem.

3.

设计策略：从“西干渠”到“西川”

Design strategy: from ‘Xigan Canal’ to ‘Xichuan’

随着城市扩张与更新速度加快，很多农耕土地在开发进程中被荒废，大量的人工干预与开发影响了整个生态环境系统，原生动植物所剩无几，生物栖息环境变得恶劣。西干渠就是一个典型案例。

西干渠改造项目，旨在修复渠道及其周边的蓝带生态系统，恢复河流水生态环境的连续性和完整性，净化水体，把生物多样性、栖息地营造纳入城市发展的重要环节，重新构建人和自然、河流的联结，为城市带来活力和场所归属感。将脏乱破败的灌溉用“西干渠”，重生为对城市、环境及居民联结，不可或缺的“西川”。

设计之初，我们首先对西干渠上中下游水质进行了取样分析，水质报告显示，渠道内水质问题主要是有机物污染和氮磷等营养物质含量较高，会引起藻类迅速繁殖，造成水体持续恶化，失去自净功能。水体的污染治理与生态系统重建也因此成为项目的最大挑战。基于设计目标与项目现况，我们制定了如下设计策略，分步解决西干渠的各项问题：

1.进行污染源研究，从源头了解并解决水质污染问题，构建生态水系统，让水体具备自身净化能力

2.同步构建西干渠延边生态环境，创造蓝绿带过渡空间与湿地空间，丰富区域性动植物物种，让整体生态循环体系形成闭环，实现永续发展目标

3.在此基础上，重建河岸空间功能，利用设计引导居民使用，让居住生活与河道生态系统和谐共处，最终实现设计愿景

With the acceleration of urban expansion and renewal, a lot of agricultural land has been abandoned in the process of development. A large number of artificial intervention and exploitation have affected the whole ecological environment system, with fewer and fewer native plants and animals left, and the environment of habitat becoming worse and worse. Xigan Canal is a typical case in this way.

The Xigan Canal reconstruction project aims to restore the blue belt ecosystem of the canal and its surrounding areas, and rebuild the continuity and integrity of the river water ecological system. More importantly, this project can help purify the water body and bring the construction of habitat environment into the essential process of city development, which would reconstruct the link between nature and humankind and create vitality and sense of belonging for the city. Last but not the least, transforming the ‘Xigan Canal’, a dirty and dilapidated irrigation canal, into a clean and indispensable ‘Xichuan’ would be an important, new bond to connect city, environment and residents.

At the beginning of the design, we sampled the water quality of the upstream, midstream and downstream of Xigan Canal. The water quality report shows that the water quality problem in the canal is mainly due to organic pollution and the high content of nutrients such as nitrogen and phosphorus, which will lead to the rapid propagation of algae and the continuous deterioration of the water, and importantly, the loss of self-purification function. Therefore, regulation of water pollution and reconstruction of ecosystem have become the biggest challenge of this project. Based on the design objectives and the existing situation, we formulated the following design strategies and try to solve the problems of Xigan Canal step by step:

1. Research on the pollution source of Xigan Canal, understand and solve the water pollution problem, rebuild the water ecosystem and make the water self-purifying.

2. Construct the ecological environment at the surrounding area of Xigan Canal and create the transition space of blue and green belt and wetland space synchronously. Enrich regional animal and plant species, make the whole ecological cycle system form a closed loop, and finally achieve the goal of sustainable development.

3. On this basis, we are trying to rebuild the spatial function of the river bank and guide the residents to enjoy and use it through the design, and make the living life and the river ecosystem co-exist harmoniously, and finally realize the design vision.

4.污染源研究

Research of pollution sources

经过多次实地调研，并与相关专家的讨论研究，我们发现西干渠改造段水质污染，主要由以下两个方面造成：

After plenty of field investigations and discussions with relevant experts, we found that the two main causes of water pollution in the reconstruction area of Xigan Canal are as follows:

一、渠道内部污染源

The internal pollution source of canal

1）上游来水污染

渠道上游水流已经带来较多农业、建筑及生活垃圾，含枯枝树叶、塑料制品、农业废弃物等，这些垃圾沿途与渠中水草和藻类形成絮状物，加剧水体富营养化和藻类爆发。

2）漂浮物污染

渠道内的漂浮污染物，包括树枝落叶、腐烂水生植物和生活垃圾等，它们互相作用共同形成了类似腐殖质的产物，一方面会影响渠道水面景观，另一方面也会增加渠道内有机物的含量，同时增加水体污染负荷，导致水质不断恶化。

3）底泥污染

渠道内厌氧污泥以及腐殖质的不断形成与沉积，使水体污染物浓度增加，底泥微生物降解有机污染物过程会消耗水中的溶解氧，同时底泥悬浮过程中吸附的污染物还会向水体扩散、释放，成为二次污染，这些影响让水体溶解氧持续减少、形成黑水、臭水，造成了水体富营养化的恶性循环。

1 )Upstream water pollution

The upstream water of canal has brought plenty of garbage from agriculture, construction and household including dry branches and leaves, plastic things and wasted farming products, which combined the aquatic plants and algae along the way in the canal into flocculation and thus exacerbating the outbreak of water eutrophication and algal bloom.

2) Floatation pollution

Pollutants floating in the canal, including decaying aquatic plants and household garbage, interact with each other and gradually form into humus-like products. This would not only affect the water surface landscape of the canal, but also increase the organic matter content in the canal and aggravate water pollution, result in the continuous deterioration of water quality.

3) Sediment pollution

The continuous formation and deposition of anaerobic sludge and humus in the canal would increase the concentration of water pollutants. The microbial degradation of organic pollutants in the bottom sediments would consume the dissolved oxygen in the water. At the same time, the adsorbed pollutants in the suspension process of the bottom sediments would diffuse and release to the surrounding water, causing secondary pollution. These impacts would continuously reduce the dissolved oxygen in the water and form black and foul water, resulting in a vicious cycle of water eutrophication in the canal.

▼改造前河道现状：上游来水、渠道漂浮物及底泥污染为其内部污染原因

The situation of canal before reconstruction: upstream pollution, floating pollution and sediment pollution are the main cause of internal pollution.

二、渠道外部污染源

The external pollution source of canal

1）生活污水

生活污水呈现有机物和氮磷浓度高的特点，其中黑水（包括粪尿和厕所冲洗水）和灰水（包括洗浴、洗衣和厨房废水）在水质和水量上也有很大差异，部分生活污水还含有重金属和有毒有害物质，水质波动较大，进入渠道后增加水体自净功能负荷，易引起渠道水体富营养化，是渠道重要外部污染源。

2）生活垃圾

渠道周边村民的生活垃圾，餐饮固体垃圾以及建筑施工过程中的废弃物等会不同程度的排入到渠道中污染水体；垃圾堆放过程中产生的大量酸性和碱性有机污染物，包括部分重金属溶解，会经由雨水冲入渠道污染水体。

3) 面源性污染

农业生产活动中施用的化肥、农药和营养盐元素等未经作物利用的，以及道路、绿化产生的地表径流污水等，这些污染物在降水、灌溉或排放过程中，通过地表径流、排水和地下淋溶等形式，进入水体而形成面源污染。它们将危害到水体的自然生态功能，使地表水富营养化及地下水的硝酸盐含量超标，影响水资源的可持续利用。

2) Sanitary sewage

Sanitary sewage showed high concentration of nitrogen, phosphorus and organic matters, in which ‘black water’ (including fecal urine and toilet flushing water) and ‘grey water’ (e.g. bath, laundry and kitchen wasted water) are largely different from each other in water quality and quantity. Some sanitary sewage also contains heavy metals and toxic, harmful substances which leads to great fluctuation in water quality. The self-purification function would be overloaded when sanitary sewage entering into the canal. Sanitary sewage is an important external pollution source of canal which can easily cause water eutrophication.

2) Household waste

The household garbage of the villagers around the canal, solid food garbage and the waste in the construction process would be discharged into the canal and pollute the water body to different degrees. Meanwhile, during the garbage stacking process, a large number of acidic and alkaline organic pollutants including dissolution of some heavy metals, could be washed into the canal by raindrops and thus polluting the water.

3) Non-point pollution

Non-point pollution includes plant-unutilized fertilizers, pesticides and nutrients applied in agricultural production process, and surface runoff of sewage generated by road greening etc. These pollutants would enter the water through surface runoff, drainage and underground leaching in the process of precipitation, irrigation and discharging, thus forming into non-point pollution. They would harm the natural ecological function of the water body, make surface water eutrophication and nitrate content of groundwater exceeding the standard, and finally affect the sustainable use of water resources.

▼改造前河道现状：生活污水、生活垃圾及面源性污染为其外部污染原因

The situation of canal before reconstruction: Sanitary sewage, household waste and non-point pollution are the main cause of external pollution.