This paper contains the following four main parts.1.A brief survey of the definition of potential evapotranspiration Et,and the relation between the potential evapotranspiration Et and the open water evaporation Eo.2.Historical review of the study of evaporation.3. The factors δ/δ+v and v/δ+v have been considered as "weighingfactors" which specify the efficiency of conversion of net radiation into energy of vaporizing water. It was considered that these weighing factors are function of mean air temperature alone, but recent study indicated that these factors are quite related to altitude. We take these factors as the functions of mean air temperature and the altitude of meteorological stations.4. For the purpose of quick calculation, We provide 6 tables for calculating the Penman estimate of potential evapotranspiration. i. e. 1) table of δ/δ+v and diagram of v/δ+v at different altitudes and for different mean airtemperatues,2) table of conversion from different mean air temperatures and relative humidities to saturation deficit, 3) table of (0.56-0.08√ed),4)table of (0.10+0.90n/N), 5) table of (0.248+0.752n/N, and 6) Table of conversion from U₁₀ to 0.26 (1+9.8×10^-3U₂).

This paper gave a preliminary analysis of the characteristic and vari ation regularity of runoff of the Yangtze river in low-flow period (from Dec. to Mar.), and the effects on the quality of the water of the Huang pu river after the intrusion of sea water.Although rich in water resource the Yangtze river hasn't much discharge during the low-flow period. The total runoff in low-flow period occupies only fifteen per cent of the annual total runoff. The mean monthly discharge in low-flow period of normal year of 50% frequency is below 15000 M³/sec. The mean monthly discharge of 75% frequency of dry year in Jan.and Feb, is less than 10000 M³/sec. Salinity varies with the quantity of the flow which comes from upstream. It becomes highly sensitive in river-mouth area when the discharge in Da Tong station is 10000 M³/sec. The salinity in river-mouth area will increase repidly if the discharge in Da Tong station is less than 10000 M³/sec. As a result, serious impacts will happen to the water supply both of Shanghai city and the industrial and agricultural bases in river-mouth area. For the planning of water supply in the Yangtze river basin,it is necessary to keep the discharge through Da Ton station above 15000 M³/sec, or at least not less than 10000 M³/sec.

中国科学院地学部地理学科组于一九八二年十月二十五日至三十日在北京召开了扩大会议,对地理研究所进行了认其的评议。评议由地学部副主任兼地理学科组组长施雅风同志主持。参加评议的除地理学科组成员陈述彭、侯仁之、周立三、谭其骧、周廷儒、黄秉维、左大康、吴传钧、杨利普、唐邦兴等同志外,还邀请了谢家泽、王乃梁、刘培桐、叶永毅、喻沧、华士乾、屠清英、刘哲明、毛德华、钟功甫、王庭梧、袁文英、赵锋、童立中、李志远、王文颖等同志。地学部的孙玉科、杨生同志以及地理研究所的前领导李秉枢、于强同志也参加了评议。

为了推动遥控遥测等新技术在地学研究中的应用,中国科学院地学部于1982年10月14日至19日在山东省禹城县召开了“中国科学院地学遥测遥感技术经验交流会”。参加会议的80余名代表中,除中国科学院地学部所属的各研究所以外,还邀请了中国科学院沈阳自动化研究所、南京土壤研究所,水利水电科学研究院,中国农业科学研究院土肥所,河北省水科所、山东省仪器仪表所、新乡地区水科所,地质部水文地质工程地质所,河南地理研究所,南宫县、封邱县、禹城县等二十三个兄弟单位参加了会议。

中国农学会农业气象研究会和中国林学会于1982年10月9日至14日在江苏省江都县召开全国林业气象学术讨论会,参加这次会议的有林业、农业、气象和中国科学院系统的科研、教学、生产单位的代表和列席代表共130余名。会议共收到学术论文120多篇,就近几年来林业气象研究取得的成果对以下几方面的问题进行深入的交流和讨论。

The present Loess Plateau dissected by the intercrossed gullies is a result of the strong erosion in the long period, which were determined by the climatic and geologic conditions. With the strongly uplifting of Qinghai-Xizang Plateau and the strengthening of East Asian monsoon since Quaternary, the climate of the Loess Plateau has been significantly differentiated in the longitudinal and latitudinal directions. The animal fossils and spore pollens reflect the characteristics of arid climate and it became drier and drier from the early Pleistocene to the late Pleistocene.Since the end of Pliocene, the intermittent uplifting of neotectonic movements and the descending of the depressions and basins on the boundary of the Loess Plateau have gradually increased the topographic gradient. Take Suide-Wubao area as an example, the gradient about 2.8% in the early Pleistocene had been increased up to 8.5% in the late Pleistocene. The erosion and deposition processes of the Loess Plateau were originated and developed in these climatic and geologic environments.By the end of the late Pleistocene, the Plateau had experienced three principal cycles of erosions and depositions, and the main gullies and loess geomorphology had been formed.Since the Holocene, the accumulation has been finished, while the developing stage of erosion has been starting. From the principle of relative accumulation, the rates of natural and accelerated erosion are deduced with the alluvial fans in different stages in the lower reaches of Huanghe. Before Tang Dynasty, the soil erosion of the Loess Plateau was only the natural process, and the accelerated rate of natural erosion was about 7.9%; since Tang Dynasty, human activities have been stimulating the acceierated erosion. The present rate of accelerated erosion caused by the human activities has been increased up to 25%.The regional differences of modern erosion on the Loess Plateau is the historical succesion and development.

Historical geomorphology is normally a study of the changes of landforms in the historical period.It has developed rapidly with its growing needs in the. production and construction of our country.Geologists, pedologists, by draulic engineers, archeologists and conservationists often consult historical geomorphologic knowledge.In theory, we know that the river meandering channel would migrate on the flood plain,but when did it cut off the meander neck? The gully would be elongated continually,but how many meters has it been elongatedy The piedmont would be buried by debris and sand coming down from the mountain slopes, but how many meters per 100 years? Historical geomorphology answers such kind of questions.Therefore, after researches on historical geomorphology, one would get some good ideas,which are helpful to the production and construction in our country. For example, the yellow River was not in one channel during the historical time.The present single channel form is the result of building dykes by human beings,so it must be noted,that its floods have destroyed the dykes and channged its course.And thus,in this article, the author suggests that the Yellow River might be branched into a fan-like channel system instead of one channel at the present day.For the fan-like channel system can make all the soil and water stay in the great, thirsty North China plain.

A variety of data from ancient documents and diaries provides a more detailed picture of climate of the 18th century. The best continuous records of climate over that period come from "weather diary", in which clear sky and duration of rain (snow) were recorded daily during the first half of the 18th century, which were observed by the officers of Hangzbou, Suzhou, Nanjing and Beijing by the order of the emperor.In the temperature derived from the above mentioned records, the ratio of snow and precipitation has been adopted to eliminate the effects of moisture conditions. Regression equations between this ratio and the temperature of Hang-zhou, Suzhou and Nanjing have been developed on the data of the last 30 years and thus temperature for the early 18th century has been obtained. It shows that the ratio of snow and precipitation days in the 20 s to 70 s in 18th century was 10-15% higher than that of today,and the derived temperature was 1℃ (Hangzhou and Suzhou) and 1.5℃ (Nanjing) lower than that of today. The 18th century was known as a warm period within the little ice age, but this paper shows that even in this warm period the temperature was lower,The groups of warm and cold years are given in table 3.The second item discussed is the phenomena in spring,Based upon the personal diaries of the 18th century, the blooming dates of Malus micromalus Makino and Prunus persica (L) Batsch are collected in table 6.In average, the blooming date in the 18th century was 6 days later than that of today and it could be estimated that the climatic belt has moved southward by 1.5 degress in latitude.Winds were observed daily in 8 directions from 1723-1769 and are compiled in table 7,It was obviously different from today's records,From November to January, the frequency of northwest wind was 10% less than that of today, and from February to October, the prevailing wind was northeast in the 18th century, but now, only in two (September and October) months northesterly prevails.By the present weather knowledge, we know that the prevailing northeast wind is often accompanied by wet wealher in the lower Changjiang valley.Based on the reports of the local histories, the deviation of index of moisture conditions of the 18th century is given in figure 3 (taking the present regime as normal).The wet weather in the lower Changjiang valley supports the result mentioned above.Thus it is possible to argue that the climatic history of the 18th century from different sources summarized above exhibits a good deal of agreement with the reality of climatic pattern.

The 1:500,000 false colour satellite images of China have been completed by the Institute of Geography,Procedures on contrast enhancment of the images with the landscape features have been done in different regions.The advantages of both satellite photographs and topographic maps were complemented. An atlas in medium scale of satellite images was compiled to present the physical features of China.The research in the compilation involved.1. The choice of the photographic originals from satellite2. The comparative analysis of the satellite images with geographic features.3. The process of contrast enhancment of the satellite images,4. The exploration of the technique for the printing plates by electronic colour scanner,5. The addition of map marks to satellite image. Consequently, the Atles has the following characteristics;1. The exquisiteness and abundance of the image involvmente can present the features of geology, geomorphology, hydrology, soil, vegetation and land use and reveal some concealed natural phenomena and their dynamic tendency.2. the technique for the Atlas was adequate,the cost of the images was very low.3. The images are easier for the users to identify in their own aspects.

In this paper, the mean monthly precipitation data series at 200 stations over the main land of China are subjected to harmonic analysis. It is shown that the annual march of precipitation over the main land of China is in general satisfactorily described by the first three harmonics, among which the first harmonie is the most important, The different regime of annual march of precipitation and the manner of transition from one regime to another are often clearly presented on the map of the first harmonic. The main features are as follows.1. The rainfall peak in the region south of the Yangtze river occurs in the latter half of May, and the normalized amplitude is relatively small, which shows that the precipitation distribution throughout the whole year in this region is relatively homogeneous.2. In North-China.North-East and some parts of Nortb-West and South. West China, rainfall peak occurs in the latter half of July or the beginning of August, and the normalized amplitude in most parts is equal to or greater than 1, which indicates that the dry season in these regions is relatively prominent.3. The transition between the afore-mentioned two regions appears quite clearly on the map. Not only the date of rainfall peak occurrence delays successively from the region south of the Yangtze river outwardly, but also the normalized amplitude increases outwardly.4. In East-China and the coastal area of South-China, the. rainfall peak occurs in the latter half of June or the beginning of July, and the magnitude of normalized amplitude in these regions is approximately the same as that in the region south of the Yangtze river.

In this paper, the integral regression method was used to analyse the relation between meteorological factors and phenophase of trees in spring of Beijing, The conclusions are as follows.1. The relations between meteorological factors and phenophase are very close.2. The factors which influence the phenophase of trees in spring are temperature, sunshine and precipitation in order of the intensity of their effects.3. If precipitation and sunshine are similar to those in normal years, they may be analysed in three time intervals: pre-winter, winter and spring.The effect of spring temperature on phenophese is the most important.At that time, the higher the temperature is, the earlier the phenophase occurs and vice versa. The temperature effect in pre-winter is similar to that in spring, but the intensity is smaller. The low temperature in winter also effects phenophase in spring, but the higher the temperature is, the later the phenophase, and vice versa. This shows that winter low temperature is also an essential condition for phenophase.4. Integral regression equation may be used to forecast the phenophase of the trees in spring.

Based on both pan-measured method and experience formula method, the conversion of water surface evaporation measured by pans at the Gutian station into evaporation from natural water body was explored in this paper from physical causes to the determination of formula. Water surface evaporation was also calculated by using the data of hydrometeorological factors.The determination of conversion coefficients and the laws of timespace variation as well as their effect factors were studied separately from the view points of both conversion coefficient and statistic correlation in the panmea-sured method. Dividing them into rising and falling temperature periods, the correlation formula between the evaporation of both ponds and pans was found out by mathematical function.The correlation between water surface evoporation and humidity grade, temperature grade as well as wind velocity was also explored in the experience formula method and then the correlation formula between water surface evaporation and hydrometeorological factors was developed.This paper can be used as references for studying the determination of water surface evaporation in the same climatie regions, the water surface evaporation can be calculated by means of the known data of various factors and the corresponding formulae, and the results might be satisfactory.

This paper briefly describes the main characteristics of physical geographic conditions in the riverhead area of the Yangtze River, in the Qinghai-Xizang Plateau, and deals with the influences of glaciers,cryopedolcgical conditions and geological structures upon stream systems and river regimens.Some regularities of variations of runoff, flood, low water, water temperature and river freeze are involved in the paper.The basic features of flood generation can be analyzed on the basis of relevant physical geographic conditions in the area. According to observation data and flood investigations, an estimation of flood peak discharge with 100 year recurrences of the rivers in the area is presented for designing the railway and highway bridges.

This paper introduces the successful experiments to determine the ¹⁴C dating of the samples by using the chemical treatment of lithium carbide(Li₂C₂). The key of the success lies in the restraining of the sublimation of lithium^ The authors suggest the principle and programme of innovating the cooling equipment of lithium reactor in this paper.The results were satisfactory.By using this method the ratio of transformation from CO₂ to C₂H₂ could reach as high as 98 percent, while by using SrC₂ method, the ratio is 70 percent.40 ¹⁴C dating data are published here.Among them four data were compared or rectified with the data measured by other laboratories.They all showed very good coincidence.

The so-called Lop Desert is distributed in the Lop Nor basin and its surronnding depressions with an area of about 50,000 sq.km The region is loeated at the innermost part of the Eurasian Continent and at the lowest part of the Tarim Basin. It is characterized by an extremely dry climate, an extremely sparse vegetation,a very rich salt-accumulation and a very low population density.Yet in ancient time it was the site of flourishing Loulan and other oases civilizations as well as the crossroad of the busy Silk Road.The dry climate of the region has been formed ever since late Cretaceous and early Tertiary. Since the Himalayan tectonic movement, coupled with the increasing uplift of the Tibetan Plateau, the desiceation has been greatly enhanced.The recent climatic trend is a continuation of slow desiccation; Yet under natural condition, the rate of desiccation is very slow and its impact on human society is negligible.The Lop depression was formed in early Quaternary. It is broadly delimited by the 900 m contour line wite its lowest point 778 m in elevation. Inside this extensive depressed area, theer smaller well-shaped depressions are identified——the Lop Nor dried basin, the Kara-holshin dried basin and the De-tama Lake basin.All these depressions have not been "wandering" during historical time. They have become lakes when filled with water and reduced to salt crust when dried.Nevertheless the braided lower channels of the Tarim-Konque-Cheerchen river system together with their end-lakes have been "wandering" during historical time. From the 2nd century B.C. to the 4th century A.D. the lower Tarim R. flowed eastward together with the Konque R. and emptied into the ancient Lop Nor.Then this combined channel turned southeastward, joined the Cheerchen R, and up to 1921 emptied into the ancient Kara-holshen Iake; the ancient Lr,p Npr was dry at that period From 1921-1952, due to human intervention, the Tarim and the Konque flowed into the Lop Nor again, with the ancient Karaholshen Lake dried up.From 1952-1972, the Tarim and the Konque were artificially separated. the latter continued to flow into the dwindling Lop Nor while the former, together with the Qarqan R., emptied into the Detama Lake. Since 1972, with the construcion of the Great West Reservoir near Takanlik, all lower channels of the Tarim-Konque-Cheerchen river system together with all end-lakes have dried up.Since the drying up of all lower channels and end-lakes the qualitty of regional environment has been greatly deteriorated.It has been featured bytwo "too little" and two "two much"——too little of water and vegetation andtoo much of salt and sand.Ef fective measures must be taken to combat these hazards as soon as possible.

Based upon the analysis of observed data,this paper shows that the length of salinity intrusion of the Yangtze Estuary is mainly controlled by runoff. During flood season the effect of salinity intrusion is negligible, while at dry season it is remarkable and 3PPT salinity water may be found throughont the South Branch.

由中国科学技术史学会地学史专业委员会主办的第一次全国地学史学术讨论会于1982年12月20-24日在广州召开.来自44个单位的73位同志参加了会议,会议收到论文75篇.这次会议是建国以来地学史研究的一次大检阅,充分显示出我国在地学史研究方面已经具有一支可观的队伍,取得了一批可喜的成果. 会议开幕式由中国科学技术史学会常务理事陈传康副教授主持.自然科学史研究所副所长严杰教授、中国地质学会地质学史研究会会长夏湘蓉总工程师作了国际上地学史和地质学史研究动态的报告.

为了把首都建设好,北京市从1979年开始,全面开展了农业自然资源调查和农业区划工作,土地类型被列为其中一项内容.土地类型调查和制图是在北京市区划办公室领导和各区、县人民政府大力支持下,由中国科学院地理研究所负责,会同北京大学地理系、北京师范大学地理系和北京师范学院地理系共同完成.1982年12月16日召开了技术鉴定会.鉴定认为:北京市土地类型是自然地理学科为农业生产服务的一项很好的集体科研成果.有关单位作了大量的地面实地调查与制图工作,文字目的明确、重点突出,成图精度可靠.

中国第四纪研究委员会与中国海洋学会于1982年11月23-27日在福建省厦门市联合召开了“中国第四纪海岸线问题学术讨论会”.来自全国沿海各省的生产、教学与科研单位的90余位同志参加了会议.会议由任美锷教授主持.厦门市副市长张可同、厦门大学副校长唐仲章教授、中国海洋学会秘书长李法西教授、中国第四纪研究委员会副主任委员王乃樑教授、国家海洋局第三研究所副所长徐沧溶等出席了会议.

The middle of the nineteenth century is the great turning point in the development of geography, marking the end of the classic and the beginning of the scientific geography. All these happened in Germany. The geography in this period synthesized all kind of concepts from the great discoveries, the rich facts of geographical knowledge, the great advances of natural science and philosophy. Geography at that time was based on the conception of integrity. The division of geography into the physical and the human was a phenomenon of later development. The establishment of the 19th century's unifying cencept in Germany had a profound influence upon the modern and contemporary geography.This paper aims at analysing the development of philosophy and matural science of that time in the relation with integrity conception.The geographical idea is synthetically influenced by philosophy ideas of kant, Hegel and Feuerbach, Marx and Engels etc., while the development of natural sciences provided the basis for establishing conception of unity for the contents of geography reguired in the connection of phenomena. Later, the authors discuss the conception of unity from the angle of the geography itself. The pioneers of the scientific geography were Humboldt and Ritter, followed by Richthofen and Ratzel. They played an active role in the development of scientific contents of geography both in theory and practice.The authors emphasize that both the regional and unifying conceptions are still the core of modern geography in spite of the tendency of branching off in the field of geography itself.

The Baiyangdian Lake is situated in a depression between the alluvial fans of yongding River and Hutuo River at the eastern foot of the Taihang Mountains. It has long been known as "a bright pearl of the Central Hebei Plain". However, the bright pearl is recently in danger of being annihilated. For this reason it is very important studying its evolutional law since 10,000 years ago and forecasting its developmental trend in the future. According to a large amount of field observations, drill records and historical-archaeological materils, a lithofacies-paleogeographic sectional map of Baiyangdian Area in the Holocene was drawn. It shows that the Holocene Series may be divided into three phases. In the Lower Holocene Series there were mainly alluvial sediments, but limnetic deposits occupied an important place in the Middle Holocene Series and the greyish black oozy layer which represented the limnetic environment possessed greater thickness and wider extent. In the upper Holocene Series the alluvium predominated again and covered over the limnetic deposits of the Middle Holocene Series.Futhermore the auther indicated that the ancient Baiyangolian Lake had undergone three stages of evolution during the last 10,000 years. In the Early Holocene the previous lake which had been died out in the dry and cold weather at the end of the Late Pleistocene rejuvenated once again around the present lake. Owing to the Atlantic Climate Optimum and the transgression in the eastern part of the Hebei Plain, the extent of the ancient lake expanded to the maximum in the Middle Holocene. However, in the Late Holocene the vast ancient Baiyangdidn lake was disintegrated, contracted step by step and died out in greater part, and only the present Baiyangdian Lake survived.The main factors controlling the expansion and contraction of the lake are climatic changes and sea level fluctuations. In addition, both the deposition of the rivers and man's irrational use of natural resources have accelerated the processes of disintegration and contraction of the lake in the Late Holocene.

In this paper the relationship between slope features and soil erosion in the loess region has been studied. Investigation shows that the angles of slopes of loess ridge and hill mostly vary from 14° to 28° The upper limit of the characteristic angles corresponds to the angle of internal friction of loess and the lower limit to half of the angle. This is coincident with the results stated by Carson (1969).The slope forms in the loess region can be separated into five types, namely straight, convex, concave, concave-convex and step slopes. The erosion position is very different on the different kind of the slopes. It mostly occurs on the downslope of the straight slope, on the mid-down slope of the convex slope, on the mid-slope of the concave slope and on the straight segments between the convex and concave elements of concave-convex and step slope.Soil erosion is greatly controlled by slope angles. The statistical analysis of the data observed in the fields shows that 15°, 26° and 45° are very important to soil erosion. The sediment yields increase with slope angles, then over 15° the sediment yields rapidly rise and washing is greatly intensified. At 26° the way of erosion changes, from the running water wash to gravitational erosion. At 45° erosion is the most intense in the slope angles between 0° and 90°. This result is supported by the mathematical deduction. The study of the three slope angles is important in both theoretical research and reasonble planning for controlling the drainage basin in a comprehensive way.

The region discussed in this article is within the realm of the southern fringe of the Taklamakan Desert. It is situated along the ancient Silk Road between Khotan and Ruo-chiang. This article was written on the basis of field investigations and analysis of historical materials.The theme includes three problems.(1) Whether or not a river existed along the southern fringe of the Taklamakan Desert in the historical period? It was recorded in "Shui-jingju" (A Commentary on ancient river system) that there was a river called"Nan ho" (south river) flowing from Khotan eastward along the southern fringe of the Taklamakan Desert and pouring into the "Lou-Lan Sea" (now Lop-Nor).This concerns an important problem about historical geography, that is, Whether or not the river system of this region had experienced a fundamental change.After analysing many historical materials and modern geographical works, we find that no Nan-ho existed there throughout historical poriod.(2) Did the number of Oasis between Khotan and Ruo-Chiang gradually increase or reduce throughout historical period? Since it reflects whether the struggle of man against desertification succeeded or failed it is an important problem too.After comparing several records in historical books from Han to ching dynasty, we find that the mumber of Oasis has increased gradually period by period.(3) East of Khotan several settlements and towns had been abolished, and the main road had been shifted too. What were the causes behind these phenomena? For solving the problems, the ruins of Andere, Niya and old Cherchen were selected and discussed in this article.

Based on the observations from the 30th of July to loth of August 1979, we have analyzed the radiation regime in Tapaishan, the highest mountain (3767 meters high) in the Tsinling Mountions.The main results are as follows.1) The variations of direct solar radiation S, diffuse radiation D, total solar radiation Q and effective radiation E with elevation are shown in Fig 3, 4 and can be described by Eg. (8), (9), (10) and (11) respectively.2) The transparency of atmosphere in the south of mountain is less than that in the north of the mountain, and, therefore, the direct solar radiation is weaker and the diffuse radiation is stronger in the south than in the north of the mountain.3) On the south slope the direct, diffuse and total solar radiation are about 16%, 60% and 23% greater than those on the north slope respectively.4) In conditions of similar underlying surfaces, the albedo of slope varies with slope orientation.It is less in south slope than in north slope.5) The mean daily albedo should be calculated by the ratio of the daily amount of reflected radiation to that of total radiation, or by formula (14). The simple method to calculate mean daily albedo by arithmetic mean may lead to serious errors.

In this paper, by using the Pentad rainfall data from 1966-1975, May-September for 121 stations in China to analyse the seasonal change of Pentad rainfall, major results are summarized as follows.1. The location of Pentad mean rainfall 10mm isohyet from July to August agrees with the Northern limit of summer monsoon.2. In China, large rain region moving from South to North is very obri-ous only in Eastern China, but it is not obvious in Western China.3. According to Pentad rainfall distribution in China, its Pattern may be divided into five types.

The design of software of surface symbol has promoted the development of thematic auto-cartography. The software is possessed of the character of serial structure in using these programs. It is composed of subprogram of surface symbol, of computing sign coordinate and of plotting out independent sign. By using the software we can design different signs of quite a lot of different thematic maps, and can automatically plot them out.The realizing process of surface symbol subprogram includes transformation of coordinate of polygon, interpolation computing of terminal point, arrangement of coordinate terminal point and recovery of system of initial coordinate, etc.To achieve the process of subprogram of computing sign seat coordinates, it is necessary to define the orientation of the drawing pen in going forward, to compute how many signs in a row and to define coordinate of every sign under the left side, etc.The besal designing mind of subprogram of independent sign is that it has arranged a data district that will store digital information of initial address of sign of every kind. Increment of coordinate is computed in the program,and coordinate value of drawing pen in advance is computed in the program too. The purpose is to plot out sign of different figures. By using different data it is possible to plot out sign which can reflect quality diversity of geographical regions or feature of numerical value.In a word, the study of software provides certain technical and scientific methods for thematic auto-cartography of agricultural map and population map, etc.

This paper reviewed the investigations on the ice and snow covers in the Northern and the Southern Hemisphere and compared the cover areas obtained by different authors. It shows that the areas calculated from more accurate satellite data set are generally in accord with other series constructed on the basis of naked observations (Table 1).The trend in the long-period variations of sea ice cover was studied in relation to the warming trend for the period from 1920S to 1940S, and to the cooling trend during 1960S in the Northern Hemisphere (Fig.2 and Fig.3).The variations of ice cover areas in the Northern and the Southern Hemisphere show great discrepancy. It is noted that recently the arctic sea-ice area has somewhat increased while the antarctic ice is in consistent decreaseIt indicated that large interannual fluctuations were observed in the snow cover area variations in the Northern Hemisphere, especially over Eurasia, the range between the maximum (1978) and the minimum (1970)accounts for about 20% of the normal.It has long been recognized that after a heavy sea-ice year the general atmospheric circulation and climate act in considerablly different way from that after a light sea-ice year. This relationship was proved recently by synoptical studies and numerical experiments. It must stress that the climatic conditions at high northern latitudes in autumn has a significant influence on the winter sea-ice cover, which is illustrated in Fig.6.

The paper gives an evaluation of the quality and quantity of the water diverted northward from the yangtze Basin. It not only answers the question on the possibility of water supply from the Yangtze Basin, but also studies the practical problem of the diversion. This paper analyzes the magnitude and the quality of the water resources of the Yangtze River and estimates the water Volume provided by the Yangtze Basin in the end of the 20th century. Through evaluation and analysis., much more water can be diverted from the Yangtze in the end of the 20th century, but the optimum scheme of diversion is on the middle stretch, while the diversion on the lower stretch will make the water quality worse before the completion of the Three-Gorge project when the discharge of Datong station is smaller than 13000M³/S.

国务院批准实施的南水北调东线第一期工程,是从长江下游江都抽水站抽水,大致沿大运河北送,经洪泽湖、骆马湖、南四湖至东平湖,输水干线长646公里(见图)。1990年工程完成后,预期提供苏北、皖北、鲁西南工农业用水,可提高现有2100万亩农田的灌溉保证率,增加旱改水的面积400万亩,使水稻种植面积扩一大到1400万亩,水稻灌溉保证率提高到90-95%,旱作物灌溉保证本提高到75%增加工矿供水7.34亿立方米^[1]。此外,还可为航运与水产的养殖提供水源。

为配合我国广泛开展的国土整治、区域规划和城乡规划工作,吸取国外有效经验,中国科学院与联合国大学联合举行“区域发展规划理论与实践”国际学术讨论会。会议在北京召开,自1983年3月29日至4月5日,历时八天。