华北平原地下水资源功能衰退与恢复途径研究

相对20世纪50年代末,至本世纪华北平原地下水总开采量由不足100×108m3/a增至211.98×108m3/a,超出地下水可利用资源量192.31×108m3/a。长期超量开采和不合理的开采布局,使地下水水位持续下降、含水层疏干体积不断增加,地下水位降落漏斗持续扩展,地下水的资源功能不断衰退的同时产生地面沉降、地面塌陷、咸水入侵等环境地质问题。采取农业节水、工业调整开采强度布局、建立应急用水机制、地表水与地下水联合调蓄、本地劣质水资源化等综合举措,修复和涵养华北平原地下水系统势在必行。     

对比求解抽、灌水过程水文地质参数的流量-时间配线法

利用基于割离井法的流量时间配线法反求抽水过程和井回灌过程的水文地质参数,并与泰斯法、裘依公式法、割离井公式法的求解结果进行了对比。结果表明,潜水含水层水文地质参数的求解选用流量-时间配线法求解精度高,可以减少繁琐的计算,结果是可靠的;对等水文地质条件下,井抽水过程求得的水文地质参数稍大干井回灌过程求得的水文地质参数,但可以用抽水过程求参方法近似求解井回灌过程的水文地质参数;运用泰斯法近似计算潜水含水层水文地质参数结果显著偏大,建议一般不予采用。     

华北平原耕作区鸟类生存制约因子初步研究

通过对华北平原耕作区不同植被类型中鸟类群落多样性的比较研究,分析了制约鸟类生存的主要因子。结果表明：在大面积种植杨树速生丰产林的华北平原农耕区,杨树幼树林木树高、胸径、郁闭度等林分因子均小于杨树老林林地,可作为鸟类食源的昆虫群落多样性水平较低,鸟类营巢巢址受到一定限制。同时由于林地多为纯林、树种组成单一、灌木及草本植物缺失,导致鸟类在食物、营巢空间上竞争较为激烈。通过种植混交林、改造纯林、乔灌草适宜搭配等营林措施,增加植被空间异质性;另外,减少人为干扰,如化学农药的使用、盗伐林木等,均可增加耕作区鸟类群落多样性。     

华北平原耕作区鸟类群落的集团结构及生态位

2004年5~8月,在河北廊坊地区进行鸟类群落多样性研究的基础上,采用系统聚类Ward方法,按照鸟类取食部位、取食方式、取食高度,分别将平原耕作区鸟类群落划分为6种、4种、3种集团类型。在栖息高度生态位宽度值上,喜鹊的最大(0.969),戴胜的最小(0.122);在栖位生态位宽度值上,树麻雀的最大(0.730),黑枕黄鹂的最小(0.272)。在生态位重叠值上,喜鹊/黑枕黄鹂的最大(0.968),而喜鹊/戴胜的最小(0.101)。在与廊坊周边自然保护区的鸟类食性集团结构进行比较的基础上,提出了鸟类群落集团结构多样性的恢复途径。     

华北平原夏玉米各生育阶段农业气候要素变化特征

基于华北平原6个农业气象试验站1981—2009年夏玉米生育期资料,以及同期48个气象站平均、最高和最低温度,降水、日照时数等逐日气象资料,采用线性倾向估计的方法,分析了华北平原近30年夏玉米各生育阶段农业气候要素的变化趋势。结果表明:(1)夏玉米出苗~拔节期的温度升高,其中平均温度、平均最高温度、平均最低温度的增幅分别为0.42℃·10a-1、0.36℃·10a-1和0.58℃·10a-1(P0.05),平均最低温度显著增加的站点多于平均最高温度显著增加的站点,温度日较差降幅为0.22℃·10a-1(P0.05);夏玉米拔节~抽雄期的温度变化不明显,温度日较差降幅为0.22℃·10a-1(P0.05);夏玉米抽雄~成熟期的平均温度、平均最高温度、平均最低温度均下降,降幅分别为0.16℃·10a-1(P0.05),0.15℃·10a-1(P0.05)和0.06℃·10a-1,其中下降显著的站点位于山东省。(2)各生育阶段降水量变化不明显,全区仅山东南部和河南中部出苗~拔节期的降水量增加显著。(3)除播种~出苗期外,各生育阶段的总辐射量均显著下降,其中出苗~拔节、拔节~抽雄、抽雄~成熟和全生育期的日均总辐射降幅分别0.83、1.10、0.87 MJ·m-2·10a-1和0.89 MJ·m-2·10a-1(P0.05),且大部分站点下降显著。     

华北冬小麦开花及成熟期变化特征分析

利用华北平原59个农业气象观测站1981—2010年冬小麦生育期资料,分析了该区域冬小麦在气候变暖背景下开花期和成熟期的变化趋势特征。研究结果表明：近30年来,华北平原冬小麦开花期和成熟期均发生了明显变化。相对1980s而言,1990s开花期普遍提前2～5 d,成熟期提前1～6 d左右,2000s开花期则一般提前3～9 d,成熟期提前1～7 d左右。因此,随着年代推进,华北平原冬小麦开花期和成熟期提前趋势在进一步加剧。相对1980s而言,1990s生育期等值线普遍北移,而2000s等值线进一步北移的趋势更加明显。研究发现,3—5月月平均气温升高是开花期和成熟期提前的一个重要影响因素。     

华北平原微咸水灌溉下土壤盐分淋洗规律与灌溉策略

合理有效利用微咸水是华北平原农业水资源短缺的重要缓解途径.基于多年试验站数据对土壤盐分动态类型、盐分淋洗条件及淋洗需水量进行了分析,并探讨了华北平原微咸水灌溉策略.结果表明:土壤盐动态淋滤型可以细分为充分淋洗型和不充分淋洗型;在华北平原冬小麦和玉米轮作制度下,只要保持土壤饱和电导率低于 6 ds/m,土壤就处于完全淋洗...     

Performance of different drought indices for agriculture drought in the North China Plain

The Palmer drought severity index(PDSI), standardized precipitation index(SPI), and standardized precipitation evapotranspiration index(SPEI) are used worldwide for drought assessment and monitoring. However, substantial differences exist in the performance for agricultural drought among these indices and among regions. Here, we performed statistical assessments to compare the strengths of different drought indices for agricultural drought in the North China Plain. Small differences were detected in the comparative performances of SPI and SPEI that were smaller at the long-term scale than those at the short-term scale. The correlation between SPI/SPEI and PDSI considerably increased from 1-to 12-month lags, and a slight decreasing trend was exhibited during 12-and 24-month lags, indicating a 12-month scale in the PDSI, whereas the SPI was strongly correlated with the SPEI at 1-to 24-month lags. Interestingly, the correlation between the trend of temperature and the mean absolute error and its correlation coefficient both suggested stronger relationships between SPI and the SPEI in areas of rapid climate warming. In addition, the yield–drought correlations tended to be higher for the SPI and SPEI than that for the PDSI at the station scale, whereas small differences were detected between the SPI and SPEI in the performance on agricultural systems. However, large differences in the influence of drought conditions on the yields of winter wheat and summer maize were evident among various indices during the crop-growing season. Our findings suggested that multi-indices in drought monitoring are needed in order to acquire robust conclusions.     

华北平原秸秆覆盖滴灌冬小麦中后期耗水规律研究

基于2013—2015年华北平原典型区连续两年田间试验,采用Penman-Monteith公式、FAO单作物系数法以及水量平衡法,研究分析了充分滴灌下秸秆覆盖与不覆盖对冬小麦棵间蒸发、耗水量、产量及水分利用效率的影响,研究结果表明:滴灌条件下秸秆覆盖显著抑制了日棵间蒸发量及其日变化波动幅度(P0.05),在冬小麦中后期相比不覆盖可减少棵间蒸发30%以上;基于田间冬小麦的气孔阻力系数实测值,采用P-M公式直接计算冬小麦日耗水量具有较高精度,其值与FAO单作物系数法计算值具有较高相关性(R~20.8);秸秆覆盖滴灌减少了7%~15%的灌溉定额,但与不覆盖滴灌相比,冬小麦日耗水量和生育期总耗水量不存在显著差异(P0.05),冬小麦4—6月份期间平均日耗水量在4.0~4.5 mm·d~(-1)之间;充分滴灌下秸秆覆盖并没有显著提高作物的产量和水分利用效率(P0.05)。     

太行山前平原地下水环境演化规律研究

本文依据河北省栾城县最新的浅层地下水水位埋深与水化学等资料 ,在综合分析研究区水文地质条件的基础上 ,系统分析了研究区内地下水水化学特征和地下水埋深分布情况。结果表明 :由于长期利用石家庄市的城市污水进行灌溉 ,区内地下水水化学场已发生明显的改变 ;长期的超采地下水 ,使得本区的地下水位埋深逐年增大。地下水的水化学特征和埋深特征表明 ,在解决本区的水资源短缺问题时 ,除考虑利用各种节水措施改变目前存在的传统灌溉制度外 ,还必须考虑区内污水灌溉对地下含水层污染的可能性 ,防止污染地下水。     

Influences of drip and flood irrigation on soil carbon dioxide emission and soil carbon sequestration of maize cropland in the North China Plain

The need is pressing to investigate soil CO_2(carbon dioxide) emissions and soil organic carbon dynamics under water-saving irrigation practices in agricultural systems for exploring the potentials of soil carbon sequestration. A field experiment was conducted to compare the influences of drip irrigation(DI) and flood irrigation(FI) on soil organic carbon dynamics and the spatial and temporal variations in CO_2 emissions during the summer maize growing season in the North China Plain using the static closed chamber method. The mean CO_2 efflux over the growing season was larger under DI than that under FI. The cumulative CO_2 emissions at the field scale were 1959.10 and 1759.12 g/m~2 under DI and FI, respectively. The cumulative CO_2 emission on plant rows(OR) was larger than that between plant rows(BR) under FI, and the cumulative CO2 emission on the irrigation pipes(OP) was larger than that between irrigation pipes(BP) under DI. The cumulative CO_2 emissions of OP, BP and bare area(BA) under DI were larger than those of OR, BR and BA under FI, respectively. Additionally, DI promoted root respiration more effectively than FI did. The average proportion of root respiration contributing to the soil CO_2 emissions of OP under DI was larger than that of OR under FI. A general conclusion drawn from this study is that soil CO_2 emission was significantly influenced by the soil water content, soil temperature and air temperature under both DI and FI. Larger concentrations of dissolved organic carbon(DOC), microbial biomass carbon(MBC) and total organic carbon(TOC) were observed under FI than those under DI. The observed high concentrations(DOC, MBC, and TOC) under FI might be resulted from the irrigation-associated soil saturation that in turn inhibited microbial activity and lowered decomposition rate of soil organic matter. However, DI increased the soil organic matter quality(the ratio of MBC to TOC) at the depth of 10–20 cm compared with FI. Our results suggest that the transformation from conventional FI to integrated DI can increase the CO2 emissions and DI needs to be combined with other management practices to reduce the CO_2 emissions from summer maize fields in the North China Plain.     

我国北方地区防治荒漠化的法律思考

荒漠化问题是当今危害全球人类最严重的问题之一。我国北方地区荒漠化土地面积为 3 2 .8万平方公里 ,约占全国国土面积的 3 .4% ,而且还在进一步发展 ,长此下去 ,令人担忧。笔者提出治理北方荒漠化的主要方面 :6项法律对策 3项政策建议。