摘  要

黄河三角洲地区受海水和高矿化度地下水的顶托和强烈的蒸发作用交互影响，成为盐渍化土地的代表区域之一，其拥有未利用土地面积约800余万亩，后备土地资源得天独厚。本文针对黄河三角洲地区目前存在的三种主导灌排工程模式，即“上农下渔”高台田治理模式（简称：台田模式）、大田漫灌深沟排碱模式（简称：漫灌模式）、暗管排碱模式（简称：暗管模式），结合案例分析，从技术效果、投资成本、后期管护及综合效益等几个方面进行了比较分析，为盐碱地治理实践优化模式的选择提供科学依据和数据支持。主要研究结果如下：

（1）首先选择典型区域开展了土壤和地下水调查，进行了研究区域现状的分析，为先进治理模式的选择提供基础数据支持。结果表明，研究区土壤0～20 cm土壤含盐量0.390～3.94 g/kg，剖面深度1.4 m范围内质地可分为2～3层，质地类型主要包括砂土、砂壤和中壤三种类型，土壤渗透系数为0.28 m/d～1.12 m/d之间，平均渗透系数为0.71 m/d，渗透等级较强；地下水矿化度在4.55～13.57 g/L之间，平均矿化度为9.20 g/L，盐度较高；地下水埋深介于1.40 m～1.57 m之间，平均为1.50 m。调查结果表明，该区域土壤需要进行盐碱地改良。

（2）其次，对于现有模式进行分析，目前黄河三角洲地区盐碱地治理模式可分为“上农下渔”高台田治理模式、大田漫灌深沟排碱模式、暗管排碱模式，本研究分别从节地效果、节水潜力、土壤改良效果进行了对比。台田模式是本地区未利用地开发初期是一种行之有效的开发利用方式，适用于低洼地带和地下水位较高的盐碱地，出地率低于60%；其对经营、维护、管理要求高，灌排和交通不便，淡水资源需求大，控制地下水位难度大，在淡水不能保障的情况下，土壤改良效果一般，且实践中坑塘养殖效益几乎为零。因此，目前对台田模式进行二次开发已经成为当前盐碱地治理的一种选择。漫灌模式采用灌排系统分设布局，灌溉工程依托于干、支、斗三级灌溉渠道，斗渠输水到田间灌溉模式；与灌溉系统相对应，排水系统采用斗排、支排、干沟汇流到外河方式，通过渠道进行大水漫灌田块，并通过排沟将灌溉水及盐碱水一并排出，此种方式灌排占地较多，出地率大约在75%左右；在水资源充足的情况下，改良效果较明显，但是由于明沟、明渠排列较多，土地分割严重，不能够适应大型机械工作。暗管排碱技术能够使土壤快速脱盐，实施一年脱盐率最高可达63.21%，可在1～2年内迅速脱盐，实现土地快速改良，同时与深沟排碱模式相比，节地增加10～15%以上，节水40%以上，结合配套建设田间防涝浅沟、强排站等防涝保障措施，可将强降雨时形成的田间积水及时排出，有效防治涝灾。因此，暗管排碱技术模式能有效填补两种排碱模式的一些缺陷，优势更为突出。

（3）本研究比较分析了三种治理模式在建设成本、使用周期和维护管理费用等方面的差异。研究结果显示，台田模式亩均投资约为3760元，暗管模式亩均投资约为3260元，漫灌模式亩均投资约3810元。台田模式一般每1～2年需要坑塘清淤和台面维护，使用寿命在10年左右；漫灌模式易淤积和坍塌，需要1年一次清淤维护；暗管模式一般每隔8～10年冲洗一次，使用期限可在30年以上，相比以上两种模式具有更长的使用周期。台田模式每万亩每10年灌排水道的清淤费用为995万元；漫灌模式的灌排水利设施每万亩每10年的维护管理费用为840万元；暗管模式每万亩每10年的地下管线维护管理费用为 487 万元。相对于传统台田模式和漫灌模式，暗管排碱每年减少了大量的维修养护费用。实践案例分析表明，采用暗管排盐模式工程投资收益率38.17%，投资回收期为4年，综合效益明显。

（4）通过对比研究和实践案例分析，本研究针对黄河三角洲地区实际，提出开展农田排灌模式转换、应用和提升暗管排碱技术治理盐碱地，从过去采用的台田模式和漫灌模式逐渐转换为地下管道排灌模式，更符合黄河三角洲地区现代农业发展的要求。有利于打造节地、节水和有效提升耕地质量的高标准基本农田样板工程，提高耕地集约化水平，推动区域生态环境良性循环，符合我国“十分珍惜和合理利用每一寸土地，切实保护耕地”的基本国策，建议进行大规模推广应用。

ABSTRACT

The Yellow River Delta area is influenced by the interaction of seawater and high salinity groundwater and strong evaporation, and has become one of the representative areas of salinized land, with an unused land area of about 8 million mu and unique reserve land resources. In this paper, three leading irrigation and drainage engineering modes, namely, "upper agriculture and lower fishery" platform field management mode, field flood irrigation and alkali pressure mode, and concealed pipe alkali discharge mode, currently existed in the Yellow River Delta region, were compared and analyzed from the aspects of technical effect, investment cost, late management and protection, and comprehensive benefits, combined with case analysis. It provides scientific basis and data support for the selection of optimization mode of saline-alkali land management practice. The main research results are as follows:

(1) Soil and groundwater surveys were carried out in typical areas to provide basic data support for the selection of advanced treatment modes. The results showed that the salt content of 0-20cm soil in the study area was 0.90 ~ 3.94g/kg, and the texture could be divided into 2 ~ 3 layers within the section depth of 1.4m. The texture types mainly included sandy soil, sandy soil and medium soil. The soil permeability coefficient ranged from 0.28m/d to 1.12 m/d, and the average permeability coefficient was 0.71m/d. Strong penetration grade; The salinity of groundwater ranges from 4.55 to 13.57 g/L, with an average salinity of 9.20g/L. Groundwater depth is between 1.40m and 1.57m, with an average of 1.50m. The survey results show that the soil is suitable for using the technique of drainage alkali in the region.

(2) At present, the saline-alkali land management mode in the Yellow River Delta can be divided into three management modes: "upper agriculture and lower fishery" platform field management mode, field flood irrigation and alkali drainage mode and dark pipe, and compared from the land saving effect, water-saving potential and soil improvement effect. The platform field model is an effective way of exploitation and utilization of unused land in the early stage of development. It is suitable for low-lying areas and saline-alkali land with high groundwater level, and the land extraction rate is less than 60%. It has high requirements for operation, maintenance and management, inconvenient irrigation and drainage and transportation, large demand for fresh water resources, difficult to control groundwater level, and the benefit of pit and pond breeding is almost zero in practice. Under the condition that fresh water cannot be guaranteed, the soil improvement effect is not so good. Therefore, the secondary development of the "upper agriculture and lower fishing" plateau field model has become a choice for the current saline-alkali land management. The deep ditch and alkali discharge mode of flood irrigation adopts separate layout of irrigation and drainage system. The irrigation project relies on three irrigation channels, namely dry, branch and bucket, and the irrigation mode is that the water is transported to the field by the ditches. Corresponding to the irrigation system, the drainage system adopts the methods of bucket drainage, branch drainage and dry ditch to the outer river to carry out flood irrigation through channels and discharge irrigation water and saline-alkali water at the same time through the drainage ditch. This method covers a large area and the discharge rate is about 75%. In the case of adequate water resources, the improvement effect is more obvious, but because of the open ditch, open channel arrangement, land division is serious, not suitable for large-scale machinery work. The hidden pipe alkali discharge technology can make the soil desalting quickly, the maximum desalting rate can reach more than 63.21% in one year, can be rapidly desalted within 1 ~ 2 years, and achieve rapid land improvement, at the same time, compared with the deep ditch alkali discharge mode, increase the land saving by more than 10 ~ 15%, achieve water saving by more than 40%, combined with the supporting construction of field water logging shallow ditch, strong drainage station and other water logging protection measures. It can discharge the field water in time during heavy rainfall and effectively prevent water logging disaster. Therefore, the technical model of concealed pipe drainage can effectively fill some defects of the two models, and the advantages are more prominent.

(3) This study compares and analyses the differences between the three modes of treatment in terms of construction costs, use cycles and maintenance and management costs. The results of the study show that the average investment per mu in the table-top model is about RMB 3,760, the average investment per mu in the dark pipe model is about RMB 3,260 and the average investment per mu in the diffuse irrigation model is about RMB 3,810. The table-field model generally requires pond desilting and table maintenance every 1 to 2 years, with a service life of about 10 years; the diffuse irrigation model is prone to siltation and collapse, and requires desilting and maintenance once a year; the dark pipe model is generally flushed once every 8 to 10 years, with a service life of more than 30 years, compared to the above two models with a longer service life. The cost of desilting irrigation and drainage waterways is 9.95 million yuan per 10,000 mu; the maintenance and management cost of irrigation and drainage water facilities is 8.4 million yuan per 10,000 mu; the maintenance and management cost of underground pipelines is 4.87 million yuan per 10,000 mu for the dark pipe model. Compared to the traditional table field model and the diffuse irrigation model, the dark pipe drainage alkaline reduces the annual maintenance costs by a large amount. Practical case analysis shows that the investment return of 38.17% and the payback period is 4 years with obvious comprehensive benefits.

(4) Through comparative research and practical case analysis, this study proposes to carry out the conversion of farmland drainage and irrigation mode, apply and upgrade the dark pipe alkali drainage technology to treat saline land in the Yellow River Delta region, gradually converting from the previous table-field mode and diffuse irrigation mode to the underground pipe drainage and irrigation mode, which is more in line with the requirements of modern agricultural development in the Yellow River Delta region. It is conducive to creating a model project of high standard basic farmland that saves land and water and effectively improves the quality of arable land, improves the level of arable land intensification and promotes a virtuous cycle of regional ecological environment, which is in line with China's basic state policy of "cherishing and reasonably using every inch of land and effectively protecting arable land".